Science method

# Numerical Modeling - Science method

Explore the latest questions and answers in Numerical Modeling, and find Numerical Modeling experts.
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I'm doing a research on numerical investigation of behavior of steel concrete composite beams. I'm using the Abaqus software in my analysis. In my model, I'm using shell element to model the Steel beam and solid element to model the concrete slab where the reinforcement has embedded in it. The steel beam and the concrete slab is connected using the shear studs which were modelled using solid elements. My question is, If we use a tie constrain in between the steel beam top flange (modelled with shell) and shear studs (modelled with solid element) what would happen to degree of freedom in rotation of the steel beam? Here I have used a tie constrain to simulate the welded connection between the steel beam top flange to the shear studs. Will ABAQUS automatically constrain the degree of freedom in rotation if I use this interaction? If so will it cause any inaccuracy in the final results?
Also, is there any possibility to use shell to solid coupling to simulate the same interaction?
Akila Dulanjalee Wijethunge Can you share your Abaqus models (.inp format)?
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I modeled a earth dam
I want to Simulation Rapid Drawdown of the earth dam at different rates with FLAC 2D software.
Who knows the FISH function or a way to do this simulation in FLAC2D software?
In my idea, upstream is transient. I think that you make a model with different levels water in upstream,rapid drawdown is very difficult for modeling. The simulation is near the real.
1. The 3D analysis and estimation of transient seepage in earth dams through PLAXIS 3D software: neural network
Numerical study of Seepage for KORD-OLIYA dam and compare by using actual data
2.
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I am attempting a numerical modeling of a pullout test for reinforced concrete. I have calculated the stiffness parameters following the FIB 2010 standard. I used cohesive contact interaction property for modeling ineraction between embedded length of rebar and concrete. However, for some reason, my bond stress vs. slip curve is not declining as expected. I also tried randomly increasing the stiffness parameters (Knn, Kss, Ktt), but the curve still does not behave as it should. Can you suggest what I should do?"
Please check, that you extract data at the right location
Make sure, that the steel does not yield
try to validate your input data - you can use differential equation solver for this => check my matlab files
have a look at the phd thesis of Roman Sedlmair from KIT Germany
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I have written a numerical model for calculating the elastic deformation of two elastic bodies in 3D static contact. The code takes the applied laod, Young's Modulus, Poisson ratio, and surface profile of each body. Calculates influence coefficients based on the equation provided by Love [1]. The problem is solved by conjugate gradient descent and elastic deformation is calculated by Discrete Fourier Transform- Discrete Convolution method.
I tested the model on ball-on-flat and ball-on-ball geometries with the same material properties of each body. I am facing the problem that the elastic deformation contour is diagonal instead of concentric in these cases. The pressure distribution normalized at Hertz Contact pressure and contact width is correct, but the deformation is not. I have double-checked by Kernal/influence coefficient matrix but can not seem to understand this behavior. I have attached the 3D plots of the example (ball-on-ball), the 3D plot of the influence coefficient at 1 point, and the contour of calculated deformation.
Any help, guidance to solve, or help in understanding the problem would be greatly appreciated.
Thanks.
A.E.H. Love. Stress produced in a semi-in nite solid by pressure on part of the boundary. Philosophical Transactions of the Royal Society of London, 377:54{59, 1929.
Influence coefficients are used in numerical simulations to determine how much influence a given node or point in the domain has on other nodes or points. These coefficients are often calculated based on the nodes' relative positions and the system's physical laws, such as the heat equation or Navier-Stokes equations for fluid dynamics.
As you've noticed, one common issue with influence coefficients is handling the boundaries or corners of the domain. In many cases, the influence coefficients near the boundaries will differ from those in the interior because the boundary conditions affect the system's behaviour.
One way to handle this is by using different formulas or methods to calculate the influence coefficients near the boundaries and interior. For example, you might calculate the first row of the influence coefficient matrix using x1 and y1 for the corners, and then use a different method for the interior points.
Another potential issue is that some numerical methods assume periodic boundary conditions, meaning that the system wraps around from one domain edge to the other. As you've described, this can result in 'continued influence' on the other edge of the domain. If your system doesn't have periodic boundary conditions, you might need to use a different method that properly handles the actual boundary conditions of your system.
It's hard to give more detailed advice without knowing the specifics of your system and the method you're using. However, I hope this gives you a starting point for understanding and resolving your issues.
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I have modeled a two-dimensional plane strain embankment in Abaqus. I did not apply any forces, boundary conditions, or displacement to the infinite element, and I defined it as CINPE4. I defined two steps for the model: the first step is static to apply gravity load, and the second step is dynamic implicit. In the second step, I applied the time history of the Loma Prieta earthquake horizontally on the base of the model. Ultimately, I observe a concentration of shear strain at the boundary between the infinite and finite elements, as shown in the image below.
In addition, I have attached my model's .inp file to this question for reference.
Hi Amir,
I checked your input file and it seems that you are using MC material def. for your soil. So, my guess was that the strain concentration is caused by discontinuity in the material behavior. Your soil block is pulling the infinite region and since it is less deformable, you get the stress concentration and plasticity in the interface region. But I tried to run your input file and in fact, the plasticity already occurred during the static step.
So, there are 2 concerns here from my pov:
1. The way you create the model. First, there is no infinite elements in the bottom of the soil. I understand what you are trying to simulate but by modelling it this way, you have no representation of the static and dynamic behavior in the vertical direction.
2. The geostatic state is missing. As you know, the soil behavior is governed by its confining stress. And it is paramount in nonlinear soil simulation. In your static step, you apply the gravity loading to the soil but there is no predefined stress in the soil. This yields incorrect nonlinear behavior because the soil strength is underestimated. Any deformation beyond this point would be considered invalid. If you are unfamiliar with this, please check the abaqus manual regarding geostatic step.
So, for your model, I recommend to apply the infinite elements surrounding the main study area. You can imagine the interface to be like a half-ellipsoid. The interface here is the line between regular and infinite elements.
And then apply the correct geostatic step. I know it can be a challenge to implement a geostatic step on a model with irregular surface. How I usually solve it is by having a preliminary geostatic computation. In this preliminary model, I apply the geostatic computation while applying fixed boundary condition to all soil (finite) region and record the reaction forces. These reactions are then used as input in the true geostatic step in the main model to stabilize the result. I don't know whether you want to go this far, so I'll stop with the details.
Cheers and good luck with the model.
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I want to simulate a discrete random  media with FDTD method.
the simulation environment is air that is filled with random spherical particles (that are small to the wavelength) with defined size distribution.
what is an efficient  and simple way to create random scatterers in large numbers in FDTD code?
i have put some random scatterers in small area but i have problem producing scatterers in large numbers.
any tips, experiences and suggestions would be appreciated.
Are you asking how to make your particles a helix/spiral shape? First, before doing that, I recommend running simulations that will just use the effective properties that your helices should give. That will let you explore device ideas without needed the complexity and inefficiency of having to resolve the spirals in your grid. Second, you will want to create a small simulation of a helix to retrieve the effective properties. This is usually called homogenization or parameter retrieval. Third, if you need to, move on to your more complicated 3D simulation.
That still leaves the question of how to build a helix in a 3D grid. One way you can do this is to create the helix in a CAD software such as SolidWorks or Blender. You can export that model as an STL file, which is just a surface mesh that MATLAB (or whatever software you are using) can import. From there, there are codes available that can import those STL files and "voxelize" them into a 3D array. If you are using MATLAB, search the MathWorks website for "voxelize" and you will find multiple solutions. Once you have that, you can create copies of the spiral in your FDTD grid. This approach will let you import even more complicated shapes relatively easily. Alternatively, you can create the spiral directly in your grid. I would do this by creating a array that has a list of points along the center of your spiral. From there, you can calculate what points your FDTD grid should be assigned to that spiral by calculating their distance to the points on the spiral. If they are within a certain distance, assign the material properties of your spiral. Otherwise, assign the material properties of whatever medium the spirals are residing in.
I am sure there are plenty of other ways to do this. If you are interested, I dedicated almost all of Chapter 1 to describing techniques for building geometries into arrays for simulation using the finite-difference method. I do not specifcally talk about spirals, but you may find some of that chapter very helpful. Here is a link to the book website:
Hope this helps!!
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I am working on Numerical modelling to simulate tribological interactions while marble cutting. If anyone familiar please guide me little bit on this.
Thanks and Regards,
Bhargav Prajwal
Hi guys,
Can anyone help me to understand, how shall i simulate the isotropic confining pressure in PFC3D using the wall servo command for triaxial testing in soil?
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How to use matlab to model permafrost priority flow and predict permafrost degradation using the dual permeability model, lattice Boltzmann model or other numerical models of priority flow
Dear friend Xuan Yangru
Modeling permafrost degradation under the action of preferential flow can be a complex process and requires a good understanding of the physics involved in the system. The dual permeability model and lattice Boltzmann models are commonly used to model preferential flow in permafrost. The following steps can be taken to consider the prediction of permafrost degradation under the action of preferential flow:
1. Define the geometry of the permafrost system: This includes defining the size and shape of the permafrost region, and any other features that may impact the flow of water or heat through the system.
2. Develop a numerical model: Using a numerical model, you can simulate the preferential flow of water through the permafrost. The dual permeability model or lattice Boltzmann models can be used to simulate the flow of water through the system. These models consider the different flow characteristics of the soil matrix and preferential flow channels.
3. Input parameters: Input parameters such as temperature, water content, and soil properties are necessary to run the numerical model. These parameters can be obtained from field measurements or laboratory experiments.
4. Run the model: After inputting the necessary parameters, you can run the numerical model and obtain results on how preferential flow impacts permafrost degradation.
5. Analyze results: Analyze the results obtained from the model to understand the impact of preferential flow on permafrost degradation. This information can be used to better understand the system and develop strategies to mitigate permafrost degradation.
Matlab is a powerful tool that can be used for numerical modeling. It has various built-in functions and toolboxes that can be used to model permafrost degradation. Some toolboxes that can be used for this purpose include the Partial Differential Equation Toolbox, the Optimization Toolbox, and the Image Processing Toolbox.
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I require few tips regarding matching the numerical model of drop weight test with the experimentally obtained data.
I will briefly discuss the drop weight model here. I have modeled a drop weight test on ANSYS workbench. The impact velocity is 2.653 m/s. The impact is happening on a rubber/jute epoxy composite which consists of 2 layers. The upper layer is rubber with modulus of 10 MPa. The lower layer is Jute epoxy composite.
The experimental drop weight curve is already obtained. The material properties of jute epoxy composite are obtained using U20MM software. Some of the stress limits of jute composite (Tensile strength, compressive and shear strength) are obtained using literature. The jute epoxy composite and rubber is modeled as solid plate. The current mesh is coarse. Please note rubber is not modeled using hyperelastic model to avoid complexity. Please see the attached file to see the force vs time curve and the difference in experimental and numerical data. Blue curve is obtained numerically.
Can anyone provide few tips in tuning the material properties/model to match the numerical data with experimental curve.
Basically you have an initial kinetic energy at impact. The strain energy and energy in plastic deformation if any must equal the initial kinetic energy minus any final kinetic energy. If you cannot find plastic part of the stress-strain curve experimentally, the best guess stress is constant between the yield point and ultimate breaking point or is straight line.
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The application of numerical models in the simulation of rock/soil cutting process and at the same time the wear on the cutting tool.
Softwares like Abaqus or Plaxis are good modeling software. Yet there are good packages for MATLAB and Python as well.
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Dear colleagues,
I am currently conducting a non-linear Pushover Analysis using a Finite Element Method (FEM) software. To ensure the accuracy of my numerical model, I am seeking to validate it against experimental results. Specifically, I am interested in calculating the error between the obtained numerical results and the experimental data and what is the limit error value.
I kindly request your guidance on the most appropriate metrics for calculating the error in my Pushover Analysis. Any advice, references, or past experiences you can share with me would be greatly appreciated.
Best regards,
Ismail
I'd like to @Genick-Bar-Meir mention, that you shouldn't forget about the FEM and experimental results are not exact themselves. First you have to estimate errors in FEM analysis and experimental research and after try to find suitable norm - its my opinion. Good luck
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Using Abaqus how to analyze diffusion rate in resistance spot welding
1. Import the temperature and cooling rate results into diffusion simulation software, such as DICTRA or Thermo-Calc.
2. Simulate the diffusion of various elements, such as carbon or nitrogen, within the welded region over time, based on the temperature and cooling rate data.
3. Analyze the diffusion profiles to evaluate the material properties of the welded joint, such as hardness and microstructure.
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#mike zero 2022 (BW
Did you try installing the latest service pack of the DHI MIKE software? There are also some hotfixes on their website.
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For comparison study of experiment and numerical work, I have to create rough surface structure modeling. which implies my numerical model would be more accurate equal to the experimental work.
But I don't know how to create a rough surface on all the inner walls of the channels (see the attachment).
Approximate dimension details:
Channel width 0.5 mm and height: 1mm
Ra: 300 micrometer
Son ich ngo Yes definitely I will try this way also.

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Hi, i am trying to run HD and ST model with MIKE 3/21 Integrated Model for a coastal area for 1 year with 600 sec timestep interval but there is an abnormal error in the middle of the year. It's 'Blow-up elevation too large'. When I examine the result, there is an anormal elevation values (about 30000 meter) in some nearshore cells. So I changed the timestep interval, resolution but didnt worked. Also, when I runned only HD model, model worked without a problem. But when HD and ST run coupled, there was an error.
Thank you.
This is probably related to the calculation of the mesh elements when the ST module is activated, which means that you should check the resolution of the mesh in the near shore areas and try to decrease it.
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Hi All
I am participating in research on numerical simulation of tall buildings' behaviour under different levels of wind speeds (in terms of magnitude). My team need secondary experimental data on the behaviour of tall buildings under wind loads. We need raw data that has just been obtained from the lab/wind tunnel without being processed. We need it to validate the numerical model on the same. Kindly good people, come to our aid. We need it as soon as possible. We can buy if it is for sale. You can contact me on +254 113 957414 or email: deenturayosman@gmail.com.
Thanks, and best regards.
Benslafa Nacera thanks a lot. I will check it out.
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I am student , I have to show the impact of urbanization on groundwater using a numerical model ( feflow) or if someone can help me with another software.
thank you
By the way... the model builder (Build3D) and particle tracker (PTRAX) I wrote (at the web link above) works with FDM, FEM, and FVM models (several different element shapes too).
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I am using the accelerometer (7264D-2KTZ-2-360) to measure the value of acceleration and multiply with mass to get impact force.
For a mass of 4 kg (timber), dropped at the velocity of 4 m/sec on an aluminum panel, I am getting the contact force of 80kN from my numerical model. And when I take acceleration as field output, it's around 1200 m/sec2.  However, I am getting the value of the acceleration of around 17 gs (170 m/sec2) from the experiment.
Back calculating my gs from the numerical model gives around 130 gs. I was wondering if such a high value of g is possible for such a low velocity of impact.
The acceleration you'll get will depend on interaction with the impact surface; i.e. a hard surface will result in higher acceleration due to shorter interaction time. In other words, you need to consider the time to zero velocity from the 4m/s impact (the deceleration). Above 100g seems high for impacting wood but conversely a metal on metal impact could results in much higher accelerations.
I'd be concerned your measurement results in a factor 10 difference. Maybe check the sensitivites of the accelerometers are correct in the data acquisition, a factor 10 out would explain the measurement difference; this could also come from a mistake between m/s2 and g values for sensitivity in the data acq.
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I need the .for file for numerical analysis
Dear Sandy J. Chaaban,
You can find the files you are looking for and the tutorials with them in the links below:
Best wishes.
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In order to represent our observations or sight of a physical process and to further investigate it by conducting experiments or Numerically models? What are basics one need to focus ? Technically, how one should think? First, thing is understanding, you should be there! If we are modeling a flow we have to be the flow, if representing a let's say a ball, you have to be the ball! To better understand it! What are others?
Aditya Kumar Mishra replication is tough though i do agree with the expert comments above that physical replication like visualization is a must one of the important criteria I feel is to To assess applicability one must always specify the requirements along with exact what attribute of a previous results of interest.
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Hi,
I am working on numerical modeling of a two-phase model for the sediment transport problem based on the SPH method.
According to previous research and works, none of them mentioned the calibrasion of numerical models and only the validation of the models were done by comparing the numerical results with the laboratory results of common samples such as dam break test cases.
Is calibrasion required for such numerical model?
What is the best option for the calibrasion of results from this numerical modelling?
Hi
It is highly recommended. Calibration of sediment transport model is as important as hydrodynamic one which can make sure and prove the model works well.
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The 'set large' model has been invoked in the Flac, the calculation step always stop when a failure zone occurs. In this case, I want to use the command of rezone to remesh the grid, but I do not know how to write the Fish function. Can anyone please tell me how to write it?
Pls refer to my command and calculation result in the attachment. Thanks!
Hi everybody,
I am facing the same problem Lei was back in 2017 with this illegal geometry error message, but I am using FLAC3D. Does anyone know any command in FLAC3D similar to rezone? Or any technical paper like Navead's one but related to same problem in 3D?
Thanks!
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Hi
I'm working on a research for developing a nonlinear model (e.g. exponential, polynomial and...) between a dependent variable (Y) and 30 independent variables ( X1, X2, ... , X30).
As you know I need to choose the best variables that have most impacts on estimating (Y).
But the question is that can I use Pearson Correlation coefficient matrix to choose the best variables?
I know that Pearson Correlation coefficient calculates the linear correlation between two variables but I want to use the variables for a nonlinear modeling ,and I don't know the other way to choose my best variables.
I used PCA (Principle Component Analysis) for reduce my variables but acceptable results were not obtained.
I used HeuristicLab software to develop Genetic Programming - based regression model and R to develop Support Vector Regression model as well.
Thanks
Hello Amirhossein Haghighat. The type of univariable pre-screening of candidate predictors you are describing is a recipe for producing an overfitted model. See Frank Harrell's Author Checklist (link below), and look especially under the following headings:
• Use of stepwise variable selection
• Lack of insignificant variables in the final model
There are much better alternatives you could take a look at--e.g., LASSO (2nd link below). If you indicate what software you use, someone may be able to give more detailed advice or resources. HTH.
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My model is a 2D axi-symmetric numerical model, with a needle electrode in the middle and a quartz capillary at the periphery, helium is ejected to the outside from the annular gap formed by the previous two. What conditions should be set for the boundary（red logo）of the needle electrode and the capillary at z=0, can anyone tell me?
Anirudh Singh Rana Thank you for your help, but I can't use zero flux boundary conditions on these two boundaries, the selection list suggests that these two boundaries are not suitable for the application. I‘m a new one and I have no idea about the reason, do you have any more detailed suggestions?
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Experimental results of the Sound absorption coefficient of material have mostly been found to be in good terms with the Theoretical models. But the calculations look confusing. With imaginary terms and differential equations.
Are there any simplified calculations and methods for theoretical modeling in acoustics?
Regarding your question on the Nocke paper, Equation 6 is derived from the previous 5 equations. The numerical value of Equation 6 depends on the values chosen for the parameters b, d, t and D. If the system is linear, the impedance should not be dependent on sound pressure, so I am guessing that the p in the denominator should not be there.
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I made a numerical model of a reinforced concrete frame in ANSYS APDL software in order to perform a PUSHOVER analysis, but the only experiment results that I got from the literature are obtained from a cyclic load experiment. However, the results are illustrated in terms of Base reaction versus roof displacement.
My question is, can I validate my numerical model with the envelope of the experimental cyclic results?
Nowadays, a variety of pushover analysis methods have been developed, including Modal pushover, Adaptive pushover, and Cyclic pushover, in which some weaknesses of the conventional pushover method have been rectified. In the conventional pushover analysis method, the effects of cumulative growth of cracks are not considered on the reduction of strength and stiffness of RC members that occur during the earthquake or cyclic loading.
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Hello,
I am using macro modelling to model using a solid element masonry triplet. When using the CDP model in ABAQUS the model runs completely and gives me satisfying results compared to the experimental data. However, I am trying to compare the CDP with the Concrete Smeared Cracking model, but the analyses terminate quite early (Probably before cracking).
The material model is defined using density, Elastic and Concrete Smeared Cracking model including Failure Ratios (as default) and Tension Stiffening, did not add Shear retention.
Has anyone from the community came across such situations? and how did you make your model work?
I was thinking that maybe besides the aforementioned parameters other damage criteria has been introduced when using the Concrete Smeared Cracking model.
Many thanks in advance and I would be please if anyone could share their similar experience with me.
Dear Ali Gamra, I tested some series of triplets within this masonry project (the simulation had been done by a colleague):
In my project "CC" I did the experiments and the simulation (smeared cracking based on experimental data).
In my opinion, this should also work on your mentioned masonry project.
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I'd like to draw a simple model on Plaxis LE designer but I did not find any guideline video that could help me to design it.
The model sample I attached. Please I hope any one can help me as fast as you can
Thanks
Nesrine El Houari Thank you but already check the manual and did not mention it
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Dear All,
Has a numerical model of the six-DOF seismic shake table been developed to predict the effect of changes in specimen characteristics on the actuator force and shaking table performance?
Has the foundation of the shake tables ever been built using isolators?
see
1-Shaking table model test and numerical analysis of a complex high-rise building
Xilin Lu, Ying Zhou, Wensheng Lu
Journal:
The Structural Design of Tall and Special Buildings
Year:
2007
2-Shaking table model test and numerical analysis of a long-span cantilevered structure
Chen, Shiming, Ge, Kang, Xue, Weichen, Lin, Yingru, Lin, Gao
Journal:
The Structural Design of Tall and Special Buildings
Year:
2018
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Dear all,
What are the factors to be taken into consideration when modeling stone columns in FLAC 3D? Are there differences between the modeling of stone columns and piles?
For using piles in FLAC 3D, alot of parameters of every pile element should be determined such as bending moment and shearing force.
If you use stone columns in FLAC 3D, only some parameters of stone zone should be determined, but bending moment and shearing force of every pile element can not be obtainedobtained and the infill materials of stone columns are totally different with that for RC piles.
Best regards,,,
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I'm trying to run Mike 21 FM HD model for a river with two boundaries. For upstream I got constant value of discharge and for downstream I set a Water Level time series which relate to the open boundary.
I wanted to test and run the model for 2 days with 30 sec time-step interval but I get an abnormal run completion in the first time step. And there is "Blow Up - Elevation too large". It shows very large water depth. Any suggestions are appreciated.
Thank you.
Thank you for your attention and your useful suggestions. John Machell Kaveh Zamani
problem solved, it was a mesh problem.
At first I generated mesh with other software and then tried to import it as a .mesh file. Everything was fine visually but there was a little problem with connectivities. MIKE needs only counterclockwise but my previous mesh generated in clockwise direction, so I changed it and model run successfully.
So if you generate a mesh and then imported it as a .mesh file in MIKE it's necessary to check element lines and make sure about connectivity directions. MIKE only accept counterclockwise.
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I am doing numerical model for FSW, I want to know which Equation of State is more compatible for FSW. EOS Polynomial or EOS Gruneisen?
This book isn't free until 12/21 (https://www.amazon.com/dp/B07Q5L1CHT) but the software and spreadsheets are always free (http://dudleybenton.altervista.org/software/FluidProperties.zip) I cover every significant equation of state in this book, including the strengths and weaknesses. Which to use depends on what behavior you're hoping to capture. So to answer your question, we would need more information. I have supplied many equations of state for industry, including the latest formulation for steam.
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The seismic pounding in adjacent buildings is an important topic in PBSD. Suggestions are requested to numerically model the interaction between the two structures: With Contact Elements? With structural interface elements? With Springs? Thanks in advance for the suggestions.
You can use a nonlinear interface relation for that allowing to gap to a certain extend and then build up stiffness from a certain displacement.
best regards Ab
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Dear all,
I am working on analytical and numerical modelling of the energy harvester. what should be the maximum percentage error difference between analytical and numerical results (voltage and deformation)?
Any help would be highly appreciated.
Regards.
Generally, you should compare the value of your error with the reported error by other researchers in your field. Then you can see whether you error is acceptable or not.
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Hi
I'm using three different performance criteria for evaluating my model:
1.Nash–Sutcliffe (NSE)
2.Percent bias (PBIAS)
3.Root mean square error (RMSE)
You can suppose that I used a regression model to estimate a time series data such as river mean daily discharge or something like that.
But for a single model and a single dataset, we saw difference performances for each criteria.
Is this possible? I expected that all of these three criteria have same results.
You can see the variation's diagram of these criteria in appendix pic.
Thanks
Due to different factors
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Hi all
Im modeling interaction of soil and reinforcement in abaqus. As you know there are two obtaining parameters for soil-reinforcement interface from direct shear test of soil and reinforcement:
1. Friction coefficient between these surfaces
for simulating mentioned interaction in abaqus I used surface to surface contact algorithm.
Friction coefficient can be defined in Tangential behavior >> Penalty method, However I can not find any way to insert apparent cohesion of interface.
It should be mentioned that Intrinsic cohesion of soil inserted as a plastic property of soil in mohr - coulomb plasticity. But apparent cohesion between these two surfaces cannot be defined in mentioned part, because this property is related in both surfaces.(its not the plastic property of one material).
Im wondering to hear any suggestion.
Alireza Akbari
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Dear researchers.
I would like please to get your opinion and expertise on this issue.
If we have a paper that deals only with a numerical results obtained from simulation.
Is there any journals could publish that paper since the experimental results can not be obtained?
I would appreciate any recommendation, expertise , advice... as I am posting that to learn from your wide knowledge.
Dear Mohammed,
many journals would publish purely numerical results. Some of them are purely mathematical like SIAM Journal on Scientific Computing, some of them belong to some specific field of application like e.g. Computer Methods in Applied Mechanics and Engineering. The key point for acceptance is the scientific novelty of your paper, which means that either your simulation results use an establish simulation technique and reveal some new effect or explain other experimental results available in the literature, or that you mainly focus on some new method of computation or a new mathematical model and the computation results merely demonstrate the good properties of this new simulation strategy. In the latter case, a comparative study with some other reference results available from the open literature or from computations using commercially available software should generally also be performed and discussed.
General hint: each journal has a website with an "Aims and Scope" section, from which you can learn, whether your specific manuscript submission would be considered suitable for the journal by the editors. Often you can also see the acceptance rate and other metrics of the journal, from which one can estimate the chances of successful publication.
Yours
Yury
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Hi
I wanna model interaction between two different material(soil and reinforcement)in abaqus.
As I know when there is no penetration between these two parts, hard contact must be defined in normal behavior however in my simulation reinforcement penetrates in soil due to loading in normal direction so I think soft contact is required in normal behavior. right??
for this purpose linear relation must be defined but I don't have stiffness (coefficient between stress and over closure).
It should be noted I tried some different value for stiffness just to see effect of that, however the analysis didn't convergence at all.
I'm willing to hear your suggestions.
Best Regards
Hi, Alireza!
I recommend checking out this paper on the use of hard and soft contact implementations through the general finite-element software, Abaqus. You can jump directly into section 7.3, which is related to your concern. Below is the link.
Chapter Contact
I hope this helps. Good luck!
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What is the best statistical index using to evaluate numerical modelling results (R2, MSE, RMSE, MAE, ... etc).
This paper describes the metrics needed:
For accuracy it is MAE if predictions were found as medians of predictive density and MSE if predictions were found as means of predictive density.
For bias it is Overestimation Percentage corrected (OPc) if predictions were found as medians and ME for the means.
You can use FEW-L1 or FEW-L2 workflow depending on the way how the forecasts were obtained.
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I want to use climatological ocean circulation data into my numerical model as open boundary condition. I found that HYCOM, SODA or CMEMS do not seem to provide climatological circulation data, and WOA only contains climatological temperature and salinity. Previous method I used is that calculated the mean current velocity by many years Reanalysis data, which is complex and need to download many daily or monthly data. So I wonder is anyone use a climatological ocean current data product? Where can I found? Or why many Reanalysis dataset don't have this?
Thank you!
A couple of websites I checked include - https://www.ncei.noaa.gov/access/global-ocean-currents-database/category.html and https://oceanservice.noaa.gov/facts/find-tides-currents.html. Although I see that the second one has historic data which may provide you some climatological data, it does seem restricted to given basins around the U.S. There is also World Ocean Database which should include directional information - that site is https://www.ncei.noaa.gov/products/world-ocean-database.
Perhaps one of these will give you the information you are seeking?
Best of luck with your research.
Mary
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Hello everyone, I would like to select specific areas to apply my model by using APDL, I want to automate as much as possible the numerical simulation and therefore I would like to work with a loop to select the surfaces and then apply the numerical model.
you can give me ideas and proposals please, you will find the geometry in image
I am familiar with C#，C，C++, and not APDL.
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I want to model a moving concentrated force to simulate the moving wheel load on the pavement in a simplified way as shown in the attachment. So, is there any way to model the moving concentrated force in Abaqus (without modeling the wheel).
Hello,
The moving concentrated forces of wheel load can be applied in ABAQUS using cyclic dynamic force. Find attached the paper on similar moving load analysis of a bridge beam subjected to moving wheel load for your reference..ok all the best..
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Hi dear researchers
Im trying to model polymeric material, but the elastic module of that is not constant and varies with change in strain, this polymeric strip(membrane element) is embedded in soil as a reinforcement and tensile load will be applied to that, so I wanna know if for my purpose using property >> mechanical >> elastic >>Hyper elastic is suitable or not, because as I know entering stress -strain test data is possible in hyper elastic.
Im wondering if using hyper elastic requires any special conditions or not or any alternative( better) way for my purpose.
Sujeet Kumar dear sujeet
thanks for your attention, but I have doubt about that, because my purpose is to use stress-strain curve in Elastic phase Not Plastic ,I mean using plasticity option for my goal seems wrong , whats your opinion?
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Hi
I know the procedure of modeling modal analysis to obtain natural frequencies(I mean using Linear perturbation step>>frequency and without defining any other loading....) but the problem is all examples I have seen is just for model made of just one material(most examples for cantilever beam) but my model is consist of two or more material( 2layer soil and layer of polymer between these soil layers), for obtaining natural frequencies in this case, my exact question is: I have to run modal analysis for each material separately or all together?!
I should mention that the polymeric membrane part does not have any type of support and its just in interaction with soil( normal and tangential behaviour), and if I run the modal analysis for this part alone natural frequencies for polymeric membrane is zero. while the soil is fixed at bottom and sides and by running modal analysis once for soil alone and another time soil with polymer,the natural frequencies are the same for both conditions. so i'm willing to know any advise and special point to obtain natural frequencies procedure for model consist of two or more materials in abaqus.
Interesting
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FLOW 3D is a one-phase numerical model with empirical equations for bedload transport, but OpenFOAM is a physics-based code.
According to my experience, modeling the sediment transport in Flow-3D needs a considerable time and computational efforts while the accuracy of your modeling ,depending on the geometry and boundary conditions, is about 10 to 20 percent in the best case.
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Hi researchers
Im trying to model dense sand which has peak friction angle and constant volume friction angle . As you k now if we plot shear stress - shear displacement(strain) of dense sand till reaching specific displacement curve ascends to the peak point(peak friction angle)and after that with slight reduction becomes constant(constant volume or residual friction angle). I wanna model the behaviour of soil accurately so my purpose is to define friction angle as a function of shear displacement. I searched and understood using SUBROUTINE (specially USDFLD) may help me but I have not work with subroutines at all and this is my first time however I linked vs code and intel R with abaqus and its completely ready for working.
Thank you so much dear chen, could you please guide me more about fist way( using field variable in abaqus) or suggest me any video or article related to this title?
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Hello everyone,
I have a very naive question. I am working with inhouse code and adapting it for combustion studies ( with flow dynamics ). However, I am unable to find any simple test case to validate the code.
Most of the studies I have come across are multistep. I thought to validate them first with premix or non-premix analytical results but have not been successful to find test case with appropriate reaction mechanism. ( I am looking for single step finite rate chemistry to be simplify things ) .
May some one suggest or recommend some means to do that.
Thanks
Hi,
We're in the process of validating a new method for simulating reacting flows, and have been taking it step by step, starting from scratch only recently. The model may not be of interest to you, but the test cases should :
- [1] > 1D premixed flame, 1 step, constant Cp
- [1] > 2D counterflow diffusion flame, 1 step, constant Cp
- [2] > 1D premixed flame, NASA Cp, detailed chemistry
- [2] > flame vortex interaction, 1 step
- more complex cases in subsequent publications
Refs (on RG)
[1] Y. Feng, M. Tayyab, and P. Boivin, “A lattice-boltzmann model for low-mach reactive flows,” Combustion and Flame, vol. 196, pp. 249 – 254, 2018.
[2] M. Tayyab, S. Zhao, Y. Feng, and P. Boivin, “Hybrid regularized lattice-boltzmann modelling of premixed and non-premixed combustion processes,” Combustion and Flame, vol. 211, pp. 173–184, 2020.
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Hi,
How the sound absorption coefficient of an acoustic absorber can be calculated using the thermo-viscous module in Comsol? When I tried to calculate the sound absorption of the Helmholtz resonator, it shows lower absorption values than the study done using the narrow region acoustics model. Compared to the thermo viscous model, the narrow region model gives better matching with the analytical model. Can anyone please help in this regard? What are the boundary conditions we have to take care of when we using the thermo-viscous module?
The numerical model and results are attaching here. Thanks in advance.
K. Mahesh You need a boundary layer mesh.
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Howdy!
I am in the process of modeling a very complex manufacturing process that involves a mixture (solid & liquid) with mechanical, thermal, optical and chemical reactions happening simultaneously. In top of that, I also need to take into account stick-slip boundary conditions and a free boundary that evolves and eventually encounters an obstacle (a mold).
I already derived a highly nonlinear system of PDEs that models its behavior and I am about to finish the numerical simulations of a linearized version of the aforementioned problem using Matlab only. Trying to solve the general problem with Matlab would be extremely difficult thus I am now in the search of the best software package that can take into account all the previous phenomena. Any suggestions would be greatly appreciated.
Thank you!
+1 to Konstantinos answer. I was able to solve rather sophisticated nonlinear dynamic problem with GetFEM++
As for your question, mechanical, thermal, optical and chemical reactions sounds for me as elastic operator(div \sigma=rhs; ) and many Laplace operators for temperature, concentration, etc in one equation system.
You may solve this in GetFem with your full control at each stage
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I am working on concrete materials, as part of my Ph.D. work, I need to carry out my thesis work with theoretical and numerical models. Please suggest me.
Thank You
if for instance your are using abaqus, the DCP is an option.
You can also use the Mander model in SAP2000 and Seismostruct
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Hi
I am planning to do numerical modeling to know the best shape of a handheld mixer with baffle plates to mix water with a gel homogeneously at the least possible time. However, I am new to numerical modeling.
Could someone guide me in the below questions?
1. What characteristics of the mix should I consider to determine the mixture is homogeneous?
2. What are some of the free tools available to do the modeling in this case?
Any input in this regard would be invaluable.
Thanks and Regards
Karthika
The following discussion seemingly can be found of some interest, concerning to your query:
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Looking for some reference to understand or learn numerical modeling for compressible fluids (such as crude oil) - flow through the fracture or space between parallel plates. Thank you.
non to my knowledge
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i want to do numerical modeling of masonry but i am confused to select the best software for masonry modeling and which is free as well.
1)autodesk robot
2) opensees
3) seismostruct
4) any other?
Assalamualaikum. As far my knowledge, you can easily model masonry wall in SeismoStruct and most convincingly you just require a student license to use SeismoStruct and no need to have a professional license with payment.
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I would like to know if the SUPG method has any advantages over the least squares finite element method?
Dear Zmour,
It can be better in term of diffusion convection reaction. My opinion is little different, the least-squares method has better control of the streamline derivative than the SUPG.
Ashish
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The concrete damage plasticity (CDP) model can predict the hysteresis behaviour of RCC structure and it is mostly used in Abaqus FEM software. This CDP model is good for the visualization of plastic deformation/localized crack pattern. It is also good for confirming the peak value of each hysteretic cycle but the basic bond-slip behaviour is not noticeable in the output of the result when the CDP is used. This is why the actual energy dissipation area/boundary is not identifiable in the present state of the CDP model. So considering this issue, a new model like CDP is needed to be adapted where it is applicable.
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I have a case, which is about internal flow with constant heat flux. Although the inlet boundary condition is laminar, the flow is passing transition and turbulent regime along the tube. As known, the intermittency term is 1 (so, admitted as turbulent inlet BC) for freestream velocity for external flow, I would like to learn that whether using the transitional SST model by laminar inlet boundary condition in the pipe is the corrects way or not.
Best regards,
The problem I faced while using SST I need to put the value of turbulence intensity at the entrance, and if I specify it to zero then my solution does not converge.
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What differential equation is the source of this numerical approximation
The basic numerical model is each patch has a vertical (Z) and a Zvelocity. Every time step it updates its ZVelocity based on the difference of its current Z and the mean Z of its neighbors. Using Von Neumann neighborhood of 4 neighbors (North South East and West) with non-periodic boundary conditions (cells on edges of the space will have 3 neighbors and corner cells with only have 2) 📷
and where can I find an explanation of why the approximation is a discretization of that.
What you are describing is an approximate solution to Laplace's equation, which applies to inviscid flow. Viscosity is insignificant in many open channel flows such as shallow water waves. To get high school boys interested in CFD show them this... http://dudleybenton.altervista.org/projects/CFD/supergirl.gif The source code is there too, including flow over an airfoil and minivan.
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Hi All
I want to simulate an ambient vibration to be used as an input to a Numerical Model. I want this to represent the vibrations occurred to the building through the wind, vehicle/human movement, etc.
The sole purpose of simulating this ambient vibration is to input it to the numerical model in order to find out the natural frequencies, mode shapes and damping ratios of the building through Operational Modal Analysis
Thank you
Hello Navindra,
If your only goal with this simulation is to find the eigen modes/frequencies and damping, a gaussian white noise bandpass filtered to the range of your suspected natural frequencies of interest (e.g. number of floors/10 estimates f0 for buildings) will do the job without fail. The magnitude of the white noise must be sufficient to excite your structure. (usually ~0.2g suffices in my experience for buildings) I suggest using Automated FDD for OMA to ease your calculations.
I hope this helps! Good luck with your research :)
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I am trying to simulate the deposition of a single extruded path using element birth and death technique. In each load step one element is activated. The initial temperature of the activated element (in the current load step) is to be the nozzle temperature. The initial temperatures of the previously activated elements is obtained from the results (temperature field) of the previous load step. The steps adopted in the model are as follows:
1. Creating & meshing the 3D model (of a single extruded strand of length=50mm)
2. Deactivating all elements (using EKILL)
3. Setting up the solution
4. Activating one element
5. Specifying initial condition on nodes
6. Specifying boundary conditions (Convection load on exterior node)
7. Specifying the necessary load step options and solving.
8. Repeating steps 4 to 7 for each activated element (using *DO loop).
I am facing the following issues:
2. When assigning initial conditions, the temperature distribution from the previous load steps can be read (using LDREAD) for the previously activated elements. However, I am unable to separately provide the initial temperature to the element activated in the current load step. The following warning message gets generated : Initial Conditions not allowed after first Load Step. Currently I have managed to avoid this issue by assigning a uniform temperature (equal to the nozzle temperature) at the beginning of solution for all the nodes (of activated as well as deactivated elements), but I am not sure of it. Is there a proper way to separately provide the initial condition for element activated in the current step?
3. Also, is LDREAD command the proper method for using the results of the previous load step as the initial condition for the current step?
Since I am new to ANSYS, any suggestions w.r.t these two issues and help in identifying the mistakes in my code/approach will be greatly appreciated.
The relevant screenshots from APDL as well as the code have been attached for reference.
Ansuman Sahu , Regarding query no. 2 in your question,
In your code, after setting the initial temperature by TUNIF, set TIME as 0. Then start a *DO loop.
The loop should run from 1st to the last load step.
Inside the *DO loop, activate (EALIVE) the required elements sequentially. To achieve this, your element numbering should follow some ordered series in the zone where they would be sequentially activated.
Then increase time by the time step size.
TIME_NOW=TIME_NOW+0.5 !!times step size=0.5
TIME,TIME_NOW !!set TIME to the current time
DELTIM,0.5,0,0 !!! Set min and max time steps
The solve inside the loop.
/STATUS,SOLU
SOLVE
Don't use LSWRIE/LSSOLVE. It may not work EALIVE/EKILL
Delete all loads in this step
End the loop
!!! In this way, your solution of each step would become the initial condition for the next step
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I know that external factors or errors in the construction of a laboratory model influence the experimental results. I modeled a dam with a numerical model (with FLAC-3D). There is a good agreement between this analysis and the experimental results. What is the compelling reason for the small differences? Also, the results are different for two different numerical models. Does only the difference in the governing equations affect this difference or is there another reason?
Experimental results are affected by the instrumental and random errors. Numerical methods are affected by the physical model selected and the parameters belong it. For example, when you are using a turbulence model some parameters can be modified and normally you only have general recommendations for do that. On the other hand, the used mesh is another source of variations in results. The Combination of mesh, models, adaption and convergence process affect the simulation. That is the reason why is so important validate numerical results against good experimental results always be possible.
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Hi dear researchers
I connected a rigid body into the part of my structure by tie constraint and then I added displacement to rigid body, in static general step every thing is fine and these two part are connected during displacement but when i run this model in dynamic explicit step , tie constraint does not work properly and rigid body and structure become separate from each other during displacement at the beginning time of this step,could anyone help?
Glad I can help, regarding why the error does not appear using Abaqus standard, I can't tell without checking the model. From what I understand, this particular type of error should appear regardless of the type of solver/step definition. If you're interested in pursuing this further, make a copy of your model with the explicit step (the one without the error) and replace the step with a general static step. If the error persists, refer to the manual.
Good luck!
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hello,
I hope that you are doing well and that the beginning of March is excellent. First of all, I would like to thank the researchers who responded to my last discussion on terrestrial albedo.
Today's discussion is about a problem I found in the numerical modeling of the convection phenomenon (heat transfer)
the goal is to dimension the prototype to be able to dimension it, so I used the finite difference method to discretize the equations of order 1 (I discretized time by a forward scheme and space by a backward scheme).
Despite this and after I wrote a program on python to be able to extract the results, I found values that are not logical for example the water temperature by heating with a radiation value of the order 500 W/m^2 -10 °C.
someone will give me an idea on what I should do or change ... ? the scheme? .........
cordially
Firyal LATRACHE
Filippo Maria Denaro Thank you very much for your answer. I am solving an equation of thermal convection like dT/dt=coefficient *dT/dz
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What is the meaning of (A.A.D.%) for reflecting the accuracy of the numerical model as compared with experimental data?
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To date, I have had the opportunity to explore several open source and private software like MFiX, Fluent, Sim-flow, Barracuda VR, PHOENICS, etc. I want to investigate 3D, hydrodynamics (include particle behavior), chemicals and radiation heat transfer maybe.
But I saw different problems when I tried to importing geometry as STL on each software.
Which software are you using when you solve this type of analysis?
Timothy Braun I am using MFiX for several months and I saw a Barracuda VR. But some reasons (like a budget :) ) I couldn't use a Barracuda.
Each software have different pros and cons for MPIC schemes. Firstly, MFiX is open-source and you can change everything that you want (like a user-defined-function). Also, MFiX has some different discretization schemes, solver types, etc.
Btw, Turbulent solvers are different. I'm working on turbulent case and chemical solvers these days. It seems Barracuda is beginner user friendly, but need to time for learning advanced things for MFiX.
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I am modeling a double pipe (concentric tube) in Ansys Fluent. The center tube contains nanofluid, and the region between the pipes is a vacuum zone. The outer tube is used for reducing convection effects. A DO radiation boundary condition is applied to the outer surface of the outer tube. I am having difficulty in modeling the vacuum region since I don't know how to specify "vacuum" in Fluent.
What is the best way to model this specific region? I just want the rays to pass through the vacuum region and reach the inner tube, the vacuum itself is not important for me.
By not solving the heat and flow equations in the between-the-pipes domain, you are technically considering the vacuum. However, in practice, vacuum is a relative concept: it is usually difficult to have an "absolute" vacuum. The pressure gauge may show few pascals. In this case, you may want to solve the heat/flow equations in your domain. In case it is still in continuum level (you can calculate the Knudsen number to decide), you can model the "natural convection" occurring between the two tubes. If so, you can model it in Fluent using Boussinesq model or ideal gas.
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Which software do you suggest for doing the numerical modeling of scour depth estimation in the cohesive soils?
I think you should go with Matlab.
Simply amazing. Python too. Take a look at BASEMENT is an easier software but could help!
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Which software do you suggest for doing the numerical modeling of scour depth estimation in the cohesive soils?