Science topic

# Numerical Analysis - Science topic

Numerical Methods

Questions related to Numerical Analysis

i want to study impact test of adhesively SLJ using abaqus, but

i couldnt know how to define adhesive material and interaction properties,

i get information about adhesive properties these below;

E(MPa) 1520

G (MPa) 565

σu (MPa) 46.93

τu (MPa) 46.86

GIC (N/mm) 4.05

GIIC (N/mm) 9.77

thickness: 0.2mm

1-is it sufficient?

2-is it correct way to analyze it, edit material> Maxs damage + Elastic>traction-->entering values.

3-if it is true, program wants from me this values for maxs damage;--> nominal stress normal-only and first and second direction

how can i put this values? How can i calculate or find? any suggestions

4- should i also do interaction properties-->contact-->cohesive properties , if yes, how can i calculate or find the Kss,Ktt,Knn values

5- Lastly there are limited information about repeated impact test for this topic on internet, how can analyze the repeated test, like, impact to deformed SLJ joint (including its previous stress values)

if someone helps, i would really appreciated..

I am an M.Tech structural engineering student working on the project ' Numerical analysis of Kath-kuni architecture ( a common masonry typology ) in Himachal Pradesh region of India subjected to earthquake loading in ABAQUS software' . The question of concern is that I am finding it difficult to input plasticity parameters for timber/ wood material that I have used in my model even after searching in various research papers. I have got only elasticity parameters and wood being an orthotropic material requires plasticity parameters and a plasticity damage model to be defined in order to understand the actual material behavior in ABAQUS software. So, kindly help me in finding the plastic properties and a damage model for timber, it would be very helpful to proceed in my current project.

Thanks and regards

📢 #specialissue #CallforPapers Calling all researchers and experts in numerical analysis and meshless methods! CMES-Computer Modeling in Engineering & Sciences new special issue “New Trends on Meshless Method and Numerical Analysis” is open for submission now.

👨🎓 Guest Editors
Prof. Ji Lin, Hohai University, China.
Prof. Fajie Wang, Qingdao University, China.

📚In recent years, in the category of numerical analysis, the meshless method has witnessed a research boom to free engineers and scientists from the difficult task of mesh generation and to reduce mesh sensitivity of solutions. Meshless methods include the kernel methods, the moving least square method, the radial basis functions, etc, such as the well-known smoothed particle hydrodynamics, the diffuse element method, the element-free Galerkin, the method of fundamental solution, the reproducing kernel particle method. The meshless method has become an attractive alternative for problems in computational mechanics, computational physics, computational chemistry, computational biology, computational materials science, etc.

🔍The main target of this special issue is to focus on the latest developments of meshless methods, such as theoretical analysis, applications, development of new methods, fast solution techniques, etc. The applications of advanced techniques such as isogeometric analysis, artificial intelligence, the physical-based numerical model, etc, in meshless methods are also welcomed.

👉 Join us in shaping the future of numerical analysis. Submit your work and be a part of this dynamic special issue. Learn more: https://www.techscience.com/CMES/special_detail/meshless-method

#NumericalAnalysis #MeshlessMethods #CallForSubmissions #ResearchOpportunity

Do

**obstacles**in a channel change the regime from**laminar**to**turbulent**while the**Reynolds number is under 2300**(approximately 1000)?Please introduce related studies.

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.

thanks in advance.

As it is impossible to use equations here, I am posting the link to my question here.

I want to simulate mixing

**two fluids**with different**inlets and velocities**in**COMSOL**. I used "**Laminar Flow**" and "**Transport of Diluted Species**" physics to do it, and my problem is that I cannot select both fluids for my domain. I have two fluids and one domain for mixing. How can I do it? Should I use "**Multiphase Flow**" physic?My combustion simulation is fully converged. The mass imbalance that Fluent calculates is 3×10^-9. However, if i calculate the mass imbalance from the average surface integrals, as (density×velocity)_avg xArea is the mass flux from inlet and outlet, the resulting mass imbalance is the order of 10^-7. What causes this deviation as its order is around 10^2. Thank you.

Hello,

We are working on the optimisation of the natural frequency of the composite beams. And using DOE L27 array has been created. Now to enter response variables' of 27 test cases, is it correct to use numerical software like ANSYS ??

I have a system of non-linear differential equations that explains the behaviour of some of the cancer cells.

Looking for help identifying the equilibrium points and eigenvalues of this model in order to determine the type of bifurcation present.

Thanks in advance.

I need a collaborator with experience in code development and, if possible, numerical analysis too.

I am currently developing an open source code in python that can be used to solve different kinds of Integral Equations.

In the last one and half years I have done some work in numerical Algorithms for integral equations with some papers already published. It has culminated to several python codes which I have used to produce the results.

The codes are all private but the results are published so I am inclined to make these codes publicly available so that others can use them at no cost and minimum effort.

I, therefore, need a fellow Researcher who has good skills in software engineering and numerical analysis to join me in this line.

A minimum requirement is the knowledge of git and python.

You can email me at nwaigwe.chinedu@ust.edu.ng

I simulate a periodic structure placed on a lossy, dispersive half-space whose relative permittivity is smaller than zero at some frequencies. Using CST 2020, I apply open boundary condition (without adding space) in the direction filled with the mentioned medium.

However, the simulation doesn't progress due to the errors. These errors are as follows:

1) "The Floquet port boundary at Zmin must be homogeneously filled with isotropic loss-free and non-dispersive material. For non-dispersive materials, please consider using the option to "Ignore losses" in the solver specials.".

2)"The Floquet port boundary at Zmin has negative material coefficients, which are not supported."

Curious to know the reason. Does it belong to the software limitations or sth?

Any suggestions or ideas are appreciated.

Thanks

Hello ResearchGate Community,

I am working on composite laminate analysis. Need to do a numerical analysis and the stacking sequence is given by the supervisor in the attached photo.

- If there is a + and - sign together (as in the case for 45 degree), then what to do?

- What to do during (0,90)?

- How the symmetry will work here?

I have some options (options given below), but not sure and don't have a clear explanation. Can anyone please help me and confirm it?

(1) 45/0/90/45/45/90/0/45/45/0/90/45/45/90/0/45

(2) 45/0/0/45/45/0/0/45/45/0/0/45/45/0/0/45

(3) 45/0/45/0/45/0/45/0/45/0/45/0/45/0/45/0

I thought to use only +45, so I have come up with these 3 options, but not sure~

Thank you a bunch in advance for your effort and time :)

I am currently doing my dissertation and I am trying to check the reliability for sub-scales I have newly created. The items comes from multiple measures as my data is from a data archive (so were collected from different studies). I have re-coded them all onto the same Likert scale but keep getting the error message "too few cases analysis not run". All missing values are coded the same (999-888) but from the help online, I am thinking it is as the missing values are scattered over numerous analysis variables? Is there any way round this? Any advice would be appreciated.....

I'm modeling a steel concrete composite beam in ABAQUS software using shell elements for the I section and solid elements for the concrete slab. Please explain me how to use tie constraint to make the contact in between these two surfaces.

How can I import

**2D**sketches from**CATIA**into**COMSOL Multiphysics**?The formats that COMSOL reads in 2D geometry are not available in CATIA.

I have generated 16 variable probability distributions in the form of a 16 dimensional NumPy array in python. How could I determine all the peaks in this function in python or using some software?

Consider the Newtonian n-body problem. An initial condition must specify the initial positions and velocities for each of the n point masses. Thus the space of initial conditions has dimension 6n. I am interested in the subset G of initial conditions which yield solutions that:

1. Are global (defined for all t > t_0)

2. Do not have have collisions or any particle escaping into infinity

3. Are real analytic: at each t there is a neighbourhood U(t) such that each position component of each particle is given by a convergent power series in t.

Note that real analytic functions which are real analytic on the whole R need not be given globally by a convergent power series as in the complex analytic case (of entire functions).

For if we extend a real analytic function to the complex numbers, such as 1 /1 + x^2, then it may well have a pole. We call such real analytic functions piecewise-entire.

What can be said about G topologically ?

When are the coeficients of the convergent power-series computable (possibly different for each member of a countable cover of the reals) ?

Are there examples of solutions which satisfy 1 and 2 but not 3, i.e. are smooth but not real analytic ?

I am trying to model excavation procedure of tunnel (D-shaped) in Abaqus (CAE). I have obtained the RF1 and RF2 from an independent analysis as given in Abaqus example (Abaqus example problem guide/1.1.11 Stress-free element reactivation). Now, my problem is that how to apply those concentrated forces ((2n+1)*2) on corresponding nodes?... Because, in my model total number of nodes (2n+1) on tunnel periphery are 129 (in the abaqus example, there are only 13 nodes). And, its changing with each trial/variation of mesh size.

So, how should I apply the concentrated forces?

i) one by one clicking each node, creating each node a set and then applied the loads from load module ? (it's tedious/repetitive. I don't want to do it) or

ii) Doing some editing in *.inp file? (But, when I tried with following format, ABAQUS is simply neglecting my edited lines:

*CLOAD

node number, direction, magnitude) or

iii) writing ULOAD subroutine?

Please clear my doubts.

Thanks in advance.

Regards,

Dipaloke

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?

when I tried to simulate a tesla valve with the compressible turbulent fluid flow for hydrogen (single-phase standard k-ε turbulent physic and heat transfer in fluid physic are used, and the study is stationary), I got the following error:

"Undefined value found.

- Detail: NaN or Inf found when solving linear system using SOR line."

What is the problem?

Hello everyone,

- So, as he mentioned in his paper that he neglected the Marangoni effect. Up until now, one can control the fluid flow with changing surface tension gradient. But since he neglected this effect, I don't know how I can enhance my fluid flow. I am having exactly the opposite fluid flow that he showed in the paper. (please see the attached screenshot of my simulation). His fluid flow is having curls in the molten pool clockwise but mine is anticlockwise. How else I can affect the fluid flow (Marangoni is out of discussion since he neglected and surface tension coefficient is assumed to be constant)?
- He also neglected the latent heat in this paper and used recoil pressure to deform the free surface. But in order to apply the saturated vapor pressure in mass flux, latent heat of vaporization is used. You can comment on it too.

I have implemented all the boundary conditions and equations mentioned in the paper. Still, not able to generate the same results. If anyone can help me with it, I would really appreciate it. I am open to discussion as well through chat system or zoom.

paper link:

I am trying to solve a time-dependent diffusion equation with finite-difference discretizations using the Newton–Raphson method. However, I encountered some problems in convergence--the solution result changes when changing time step size. Here I want to find some coding examples to refer to. Thank you.

Re: ARTICLE: "Should Type Theory replace Set Theory as the Foundation of Mathematics?" BY

Thorsten Altenkirch

Type Theory is indicated (by the author) to be a sometimes better alternative and a sometimes-replacement for regular set theory AND thus a sometimes better replacement for the logical foundations for math (and Science). It seems to allow turning what is qualitative and not amenable to regular set theory into things that can be the clear particular objects of logical reasoning. Is this the case? (<-- REALLY, I am asking you.)

It is very rarely, if ever, I have addressed anything that I did not have a good understanding of; BUT, here is the exception (and a BIG one). (I HAVE VERY, VERY little understanding of this Article -- even from the most crude qualitative standpoint. You would say I should have researched this more, but it in not my bailiwick , only more confusion, on my part would likely occur, "shedding no light". My sincere apologies. ANYHOW:

:

If indeed things are as the author, Thorsten Altenkirch, says: it seems different things (other than those related to standard propositions in regular set theory) could widen the use of set theory itself yet retaining (including) all of regular set theory (with all of its virtues, as needed). BUT, in addition it is indicated it could be applied to areas (PERHAPS, like biological and behavior science) where present set theory (and the math founded on it) cannot now be applied.

"[ The ] type theoretic axiom of choice hardly corresponds to the axiom of
choice as it is used in set theory. Indeed, it is not an axiom but just a derivable
fact."

More Quoting of the author: "Mathematicians would normally avoid non-structural properties, because they entail that results are may not be transferable between different representations of the same concept. However, frequently non-structural properties are exploited to prove structural properties and then it is not clear whether the result is transferable." .... "And because we cannot
talk about elements in isolation it is not possible to even state non-structural properties of the natural numbers. Indeed, we cannot distinguish different representations, for example using binary numbers instead." ... "we can actually play the same trick as in set theory
and define our number classes as subsets of the largest number class we want to
consider and we have indeed the subset relations we may expect. ... Hence Type Theory allows us to do basically the same things as set theory"
... as far as numbers are concerned (modulo the question of constructivity) but in a more disciplined fashion limiting the statements we can express and prove to
purely structural ones."

"we cannot talk about elements in isolation. This means that we cannot observe
intensional properties of our constructions. This already applies to Intensional
Type Theory, so for example we cannot observe any difference between two
functions which are pointwise equal." ...

"...Hence in ITT (regular set theory) while we cannot distinguish extensionally equal functions we do not identify them either. This seems to be a rather inconvenient incomplete-
ness of ITT, [ (common set theory)] which is overcome by Type Theory (HoTT)"

"[It] reflects mathematical practice to view isomorphic structures as equal.
However, this is certainly not supported by set theory which can distinguish
isomorphic structures. Yes, indeed all structural properties are preserved but
what exactly are those. In HoTT all properties are structural, hence the problem
disappears. ..."

"While not all developments
can be done constructively it is worthwhile to know the difference and the difference shouldn’t be relegated to prose but should be a mathematical statement." [AND}: ...

"Mathematicians think and they often implicitly assume that
isomorphic representations are interchangeable, which at closer inspection isn’t
correct when working in set theory. Modern Type Theory goes one step further
by stating that isomorphic representations are actually equal, indeed because
they are always interchangeable."...

..."The two main features that distinguish set theory and type theory: con-
structive reasoning and univalence are not independent of each other. Indeed
by being more explicit about choices we have made we can frequently avoid
using the axiom of choice which is used to resurrect choices hidden in a proposition. Replacing propositions by types shows that that the axiom of choice in many cases is only needed because conventional logic limits us to think about propositions when we should have used more general types."

Oh, here's the link to THE ARTICLE:

Consider the powerful central role of differential equations in physics and applied mathematics.

In the theory of ordinary differential equations and in dynamical systems we generally consider smooth or C^k class solutions. In partial differential equations we consider far more general solutions, involving distributions and Sobolev spaces.

I was wondering, what are the best examples or arguments that show that restriction to the analytic case is insufficient ?

What if we only consider ODEs with analytic coeficients and only consider analytic solutions. And likewise for PDEs. Here by "analytic" I mean real maps which can be extended to holomorphic ones. How would this affect the practical use of differential equations in physics and science in general ? Is there an example of a differential equation arising in physics (excluding quantum theory !) which only has C^k or smooth solutions and no analytic ones ?

It seems we could not even have an analytic version of the theory of distributions as there could be no test functions .There are no non-zero analytic functions with compact support.

Is Newtonian physics analytic ? Is Newton's law of gravitation only the first term in a Laurent expansion ? Can we add terms to obtain a better fit to experimental data without going relativistic ?

Maybe we can consider that the smooth category is used as a convenient approximation to the analytic category. The smooth category allows perfect locality. For instance, we can consider that a gravitational field dies off outside a finite radius.

Cosmologists usually consider space-time to be a manifold (although with possible "singularities"). Why a manifold rather than the adequate smooth analogue of an analytic space ?

Space = regular points, Matter and Energy = singular points ?

Can anyone please help me write a MATLAB program to find the temperature distribution (By numerical method) across a composite building wall subjected to periodic boundary conditions?

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

I am trying to model a fault plane within an infinite soil/rock medium with a prescribed in-situ stress state to see its impact. How can I input my in-situ stresses into ABAQUS? any help appreciated thanks!

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?

my numeric data is in

**1, 0 & 0.5**. how can I perform structure analysis?I want to solve a nonlinear equation G(W)=0 via Newton-Krylov-hookstep method, which comes from the attempt of finding a periodic orbit of the 2D flows in a rectangle。

I had found a possible approximate value W0, and |G(W0)| is about 7. But now the Newton-Krylov didn't lead to a fast decrease of |G(W)|, and it stagnates around 6.9~7.

Is there some remedy I can do to make |G(W)| decreases fast enough?

Thank you very much.

P.S. The variable 'W' represents the FFT coefficients of w(x,y) in MATLAB, thus the real residual should be |G(W0}|/N^2, and the corresponding values of w(x,y) is quite satisfactory for the attempt of finding a periodic orbit. In my opinion, it's a pity to discard this value, though I have to agree that it may be a bad initial guess in reality.

To the best of my knowledge, the first rigorous approach was presented here

and all studies followed that approach.

But I wonder what about the approach to follow in case of an integral equation that is discretized?

Have you ever seen some study wherein the modified integral equation is illustrated?

Dear Colleagues,

Are You by any chance familiar with any data/papers on the subject of RC or prestressed circular hollow sections (in columns, beam-columns, beams) subjected to preferably both axial force and bending moment or maybe under pure bending at worst. If Yes please share the links in the comments below.

I am interested mostly in experimental research but numerical analyses would also be appreciated.

Best Regards,

Bartosz Grzeszykowski

Hello friends

Nowadays I am trying to use Code_Aster to simulate CABLE . I want to know how to add a force like this F=0.5*velocity^2 on selected nodes?

And how can people add a triangle distributed force on a moving cable whose coordinate is changing with time .

Thanks for your help in advance.

Hi

I wanna solve partial differential equation in terms of x and t (spatial and time), As I know one of the most useful way for solving pde is variable separation. well explained examples about mentioned way are wave equation, heat equation, diffusion....

wave equation is Utt=C^2 .Uxx

in other word; derivatives of displacement to time, equals to derivatives of displacement to spatial multiplied by constant or vice versa.

however my equation is not like that and derivatives are multiplied to each other.for example : Uxx=(1+Ux)*Utt

Im wondering how to solve this equation.

I will be thankful to hear any idea.

I want to solve analytically a coupled 2nd order space-time problem, originated from an optimal control problem. One of the problems is forward, another is backward in time. For example, (i) $y_t-y_{xx}=u, y(x,0)=0, y(0,t)=0, y(1,t)=g(t)$ (ii) $-p_t-p_{xx}=y, p(x,T)=0,p(0,t)=0, p(1,t)=h(t)$ with the coupling condition $p(x,t)+c*u(x,t)=0$ in $(0,1)\times (0,T)$. I have tried separation of variables, but it is getting complicated, any suggestions?

I'm planning to perform a low-velocity impact analysis on a sandwich composite consisting of top and bottom face sheets (Unidirectional fibre reinforced) with 4 plies each and a core (aluminium). The thicknesses are small relative to the other dimensions. After going through various materials, I'm still confused whether which one among the following combinations of elements I should go for -

1) SC8R (Core and face sheets)

2) SC8R (Core) and C3D8R (Face sheets)

3) SC8R (Face sheets) and C3D8R (Core)

4) C3D8R (Core and face sheets)

SC8R - Continuum Shell Element

C3D8R - Solid Element

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

Dear friends

I am trying to use CODE_ASTER , a finite element software to simulate a fish cage‘s movement. I am using HHT method to solve the problem with alpha=-1/3. My force is added with Morison equation like this : fn=0.5ρC

_{d}LDV|V| and it is added at each selected time step(defined before calculation).When the velocity is under 0.5m/s, my job seems well ,but when I change a higher velocity, the deformation become pretty bad, the cage is oscillating . In my job, there is no structural damping ,only the numerical damping is added. I am wondering what will cause this problem? If it is the problem of implicit solver or the way I add the force?

There is a GIF of the problem. I hope to get some ideas.

when the analysis is done by the Axisymmetry model, the out put of force vs displacement is obtained by the kN/rad. simply we multiply 2pi and get force in kN. in this case square footing (150x150mm) is half.

but when the same analysis is done the Plain stain model, the output is obtained kN/m. so which length of width is multiply to get force or how to get bearing capacity. use square footing 150x150

Note:

pictures are attached. please explain.

In a flow over rotating cylinder simulation, if the cylinder keeps changing its shape with respect to different angular position during rotation. How to specify the shape changes of the cylinder in the transient analysis case?

Dear researchers.

I am studying the vibration of a blade in function of rotational velocity.

the blade feedback through ANSYS is presented in the attached picture.

Why the feedback is instantaneous in the numerical study while in the experimental it is a continuous sinusoidal (Measure with Laser vibrometry)?

is there any thing wrong I am doing in the numerical analysis? how to compare in this case

Hello dear colleagues,

I couldn't figure out what are the required material properties to perform fatigue simulation using ANSYS SMART. What should I add to predefined structural steel to proceed with the simulation?

Thank you very much for your help.

Dear scholars,

my topic of interest is the numerical analysis of weldments with special interest in material heterogeneitiy (base material, coarse- & fine-grain-zone, filler material). For this purpose, i modeled a quarter of a 3D-butt-welded sample under displacement load. Each particular zone was modelled with specific material-data (for all in general: multilinear-plasticity; isotropic hardening), Hollomon-extrapolation was used to obtain realistic results.

The results of the numerical simulation show huge discontinuities in zones of material transition when it comes to the internal stresses (for von-Mises-stress, see the attached PDF). In my opinion, these discontinuities have their origin in the simple fact, that the nodes on the borders between two different materials can't "smooth out" the two differing material behaviours. This arises from the fundamentals of FEA and can't be "improved" by ANSYS-specific modelling steps.

Am I right with my conclusion or does anyone have any advice for me in this context? Any advice is highly appreciated. In case there are still questions, I have attached my APDL script. Otherwise don't hesitate to ask, if more information is needed.

The basic facts of my numerical approach:

- Calculation using APDL script in ANSYS

- Notch stress analysis on 2D/3D bodies

- Meshed with quadratic elements

>>> 2D: Plane183

>>> 3D: Solid186 & Solid 187

- Multilinear-plasticity material models with isotropic hardening

- Due to lack of experimental data: stress-strain diagrams of the 4 material domains from secondary source.

>>> Hollomon extrapolation already performed there

Many thanks for any help.

Timo Siemer

Is there a best method for simulating a tensile test with a strain rate of 1mm/min that experimentally took minutes while obtaining accurate break results? Is it necessary to run at a specific strain rate like when testing experimentally, or could I run any displacement in any end time and get an accurate stress-strain curve?

Hello, I am attempting to use ANSYS to simulate the tensile testing of a polymer according to ASTM D638. This entails a strain rate of 1mm/min.

I'm having the following issues:

- resources do 1 of the following: a) use explicit dynamics using very fast strain rates eg. displacement = 0.01m, time = 0.001s, or b) they use static structural with a displacement and get a result with no fracture, though it seems much more common in literature.

Following a), my imported material causes an error when break would be expected, where time step goes too small or energy error is too high, but no break happens. Then, if I try to apply the displacement over a long study time, like 1mm/min by applying a displacement and increasing the end time to ~60s, or by applying a velocity of 1mm/min and setting a 60s end time, I get computation times of nearly days and then it fails quite early while saying "energy error too large" or "time step too small".

To reiterate, is there a better, more time-efficient method for performing this? Am I understanding end time and strain rate wrong? Pictures can be added for clarification if requested.

When solving Ordinary Differential Equations in time using, say R, is common to find ourselves in a part of the parameter space that does not allow for correct solutions. For simple models it is easy to derive parameter conditions in a way that we only end up with appropriate solutions.

Consider a complex ecological system with many species, that is, multiple ODEs. It can be difficult or impossible to arrive analytically at the intervals for parameters that lead to proper states (i.e. all species abundances should be positive for example). We can try to choose random parameter combinations until we get results that make sense, but often times we get hyper-exponential blow-ups in growth.

**Is there any numerical or analytical trick that can help in avoiding these solutions?**

We are trying to establish a method to calculate the diffusion coefficient of resin materials. What methods are available to derive the diffusion coefficient of composites from the diffusion coefficient of matrix? The filler we are using is glass and the resin is PPS. I know that the Springer method exists, but are there any other formulas that take into account the angle, volume, and particle size of the filler?

Dear Researchers, I ask for help;

This is in COMSOL Muliphysics ver.5.6

I am tryring to solve a model of an Energy Power Cable which is burried in the soil, is a 2D model

I choose to couple the phenomena of: -Electrostatics, -Electric Currents and -Heat Transfer in Solids (this last one is coupled using the 'Electromagnetic Heating' sub-module within the AC/DC module).

I already could solve the Electric Potential and the Electric Field (both, E and D) distribution,

But as much as I tried, I cannot understand how to solve correctly the Heat Transfer part of the model

The coupled phenomenon of Heat Transfer is due to the Joule Effect, due to the Electric Current/Voltage passing across the conductor.

When I solve for the Temperature Distribution I get :

- All the model is at the same temperature

- The value of the Temperature is negative, and

- This value is x10^18 K

Defenitevely something is wrong, very likely with the boundary condition of the Heat Source I'am trying to stablish.

It could be an evident-to detect mistake, but I cannot understand it

I am attaching the pictures

The first one is of the view 100% zoomed out, to see the complete geometry (I am including the seccion of the soil in my model),

and the second image is the view zoomed in of the geometry of the Cable

Please, does any know, and can help me, Why I cannot solve this model correctly ?

I will really appreciate it,

Best Regards !

Dear Researchers :

Recently I asked an official quotation (with all the requiered concepts) from ANSYS and from COMSOL to implement the same type of License and the same set of modules, the scheme of the License are not exactly the same , but very close ,

For both software I'm interested in being able to solve applications with the Structural Mechanics Module and the Electromagnetic Module

But in general, If I place both final prices in the same footage, I realise ANSYS is always more expensive (at least today) than COMSOL (roughly between 35 - 40 % more)

Does anyone with experience in this may know one of the reasons why this is so ?

Regards !

Dear.

Since I am interested ;ore in understanding the way sensors work, so I would like to start a numerical analysis for several sensors to try to combine that with experimental results.

an example of the sensors I would like to simulate is:

My aim is to use the simulation to understand at the first place and a starting point toward the development of those sensors.

any tools and any advice are welcome.

Thanks in advance

Hello everyone

Recently, I've been working on constructing the waveform for the simple PCB interconnect by means of

**existing algorithm**, which means I don't want to use the commercial software.To be simple, I suppose the topology is just

**TX + transmission line + RX (**See Fig. 1**)**At the beginning, I just wanted to quickly estimate the waveform with ideally initial waveform

**(**See Fig. 2**)**Unfortunately, I had no idea to estimate the

**TX output impedance**and**RX input impedance.**Eventually, I thought I had to build the waveform by means of interpreting the IBIS models.

There are [Pullup], [Pulldown], [POWER Clamp], [GND Clamp],... in the IBIS.

However, I don't know how to use them to construct the waveform and get the internal impedance.

My question : How to do that with the IBIS information?

(Suppose the IBIS is

**4.2 version)**Thanks for your kind reading.

I am analyzing two adjacent interconnected rectangular channel flow patterns. The image of my numerical model is attached below.

The fluent solver was pressure based, and velocity formation was absolute. The SIMPLE algorithm was used. Laminar regime was selected and energy equation was kept on. Boundary conditions were checked carefully. Inlet velocity and pressure outlet conditions were applied. Uniform Heat flux was applied at the bottom face. Solid fluid interfaces are thermally coupled. Second order upwind equations were used for energy and momentum equations. The residuals were kept 10^−5 range, and the solution was fully converged.

I have drawn a centerline inside a mini-channel for observing velocity distribution. Is my solution right? and velocity profile having zigzag is okay? if not, pls explain.

I want to do comprehensive study of errors in variables from both numerical analysis and statistical viewpoint and compare the results with regression for selected parameter estimation problems in my domain where it is expected to perform better in terms of accuracy. These problems are of type linear and non linear regression. I want to check if the method under study is an improvement over generalized least squares. I am including multiple factors like accuracy, computational efficiency, robustness, sensitivity in my study under different combinations of stochastic models. What kind of statistical analysis/ experimental design/metric/hypothesis test is required for a study of this nature to establish superiority of one method over another(to make a recommendation of one method over another for a particular class of problems)

I am simulating a rectangular water channel. To validate my numerical results, I want to present a graph containing the enhancement of Nu for this channel with several Re. Then, I compared this variation with another's study where the hydraulic diameter is not the same, however, both channels are mini-channels.

**For example:**

pls download the paper given below:

**In this paper - Under Section 3.1:**

The authors validated their model with Fan et al., Ho et al, and Moraveji et al. However, their hydraulic diameters are not same. How is this comparison valid?

I am doing 3pt bending test in LS-Dyna with a glassfibre-epoxy sample. So it is a non-linear dynamic (quasi static) problem. I assume it is a implicit problem since the event is slower and the effects of strain rates are minimal. But my professor used explicit control card to solve this. what difference can it give?

Hi

Im modeling test which first phase of that is displacement control (adding constant rate of displacement) and the next phase is load control (adding cycling load) ,more precisely after reaching specified load by constant rate of displacement cycling load must be applied,however something seems wrong.cycling load doesn’t being applied correctly, and in plot stress ,stress stays constant (stress at the end of first phase)in cyclic phase. so I deactivated the displacement control in following step(cyclic phase) but in this situation stress drops to zero, and for the last attempt I activated that again but I modified it too and made the displacement in following step zero but it didn’t help and stress decreased slowly, it must be mentioned I modeled cycling load alone in first step to see if the problem related to that but everything was correct and cyclic load applied correctly in this situation I will be thankful for your help.

While performing numerical analysis using Ansys workbench software. I have performed compression analysis in both static structural and transient structural analysis. In both the cases of the results. I have observed the stress concentration is high at the boundaries of the cylinder sample. why the stress concentration is high in the compressive samples ?

Dear

I am performing a series of structural analysis test through software, for some model I already have the experimental results so the selection of mesh is related to this results, the good mesh is the one who gives the best approximation to the desired results but....

In Case we are testing a new design or a new structure without any previous knowledge , how to know the correct mesh?

I want to solve a second-order non-linear and non-homogenous order differential equation using the non-linear shooting method and fourth-order Runk Gutta using Python?

Thank you for your help!

I would like to know if the SUPG method has any advantages over the least squares finite element method?

Thank you for your reply.

I am currently working on PCF design and numerical analysis to achieve high negative chromatic dispersion and low confinement for high-speed optical telecommunication networks. Any simulation assistance as to how to use the COMSOL multiphysics tool to achieve these objectives?

Dear Colleagues and Authors,

plenty of problems in mathematics, economics, physics, biology, chemistry, and engineering, e.g., optics, radar, acoustics, communication theory, signal processing, medical imaging, computer vision, geophysics, oceanography, astronomy, remote sensing, natural language processing, machine learning, non-destructive testing, and other disciplines, can be reduced to solving an inverse problem in an abstract space, e.g., in Hilbert and Banach spaces. Inverse problems are called that because they start with the results and then calculate the causes. Solving inverse problems is a non-trivial task that involves many areas of Mathematics and Techniques. In cases where the problem is ill-posed, small errors in the data are greatly amplified in the solution, and therefore, regularization techniques using parameter choice rules with optimal convergence rates are necessary.

Currently, I am editing a special issue on "Numerical Analysis: Inverse Problems – Theory and Applications 2021" with a Switzerland-based "Mathematics" MDPI Journal.

I would like to draw your attention to this possibility of submitting research articles:

Please let me know if you need any help.

Thank you for your kind consideration,

Christine Böckmann

Multi-step methods implicitly use one-step methods as a starter, but we still expect better approximation using the multi-step method. I want to know why?

Do we have any empirical model to model the combined effect of carbonation and chloride attack in concrete concerning time-dependent temperature, relative humidity and concentration of carbon dioxide?

Hello

To validate the results of modeling by Abaqus software with experimental results, how can estimate the Chaboche hardening coefficients from the hysteresis curve?

The material is steel.