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# Multiphase Flow - Science topic

Explore the latest questions and answers in Multiphase Flow, and find Multiphase Flow experts.

Questions related to Multiphase Flow

Has anyone tried modelling multiphase flow (interFoam solver) using LRR or SSG turbulence closure in OpenFOAM? I want to discuss about it.

Subhojit

Using

**COMSOL**software to realize the numerical simulation of multiphase flow problem, in the field of microfluidic research, how to realize the simulation of the**dynamic contact angle**of droplets?I am performing a simulation in Ansys fluent using multiphase flow settings for two phase flow problem and with out multiphase flow settings for single phase flow. The results differs heavily and huge enhancements in multiphase flow.

Hi dears I encounter some problems in growth rate udf and I share them. I hope someone help me out. I have a growth rate in population balance which depends on the diameter: G(L)=(Rp*L0*L0*L0)/(3*ro*di*di*di) Which L0 is initial diameter and di is next diameter due the growth. I set initial diameter, but next step time initial diameter will change and I don't know how udf can recognize new diameter. Moreover, how I can set di?

bests

Mohammadhossein

Hello all,

I intend to perform a CFD analysis of the well-known bridge pier scour problem. I am considering two software packages for this purpose: Ansys Fluent and Flow 3D. I am trying to explore the pros and cons of each package for my case.

I would appreciate your comments on any of the following.

1- In order to make a sound comparison, I need to understand the modelling details implemented in Flow 3D, especially a clear description of the way sediment transport is modelled and coupled with the hydrodynamic solver, and how the interphase interaction is realized. Despite lots of research, I have not been able to find detailed information on this.

2- Any study on comparing the performance of these two packages for bridge pier scour problem.

Regards,

Armin

The pressure boundary in multiphase simulations is important. A widely used pressure boundary may be to enforce the normal gradient of the pressure to be zero. However, this is not always physical and the accuracy is poor. How to define the pressure boundary more physically, in particular, the partially wetting boundary condition is involved together. Have any suggestions?

Hello all,

Source terms have been known to cause reliability issues in numerical methods affecting therein convergence and accuracy. I am currently facing a similar challenge when trying to solve a Poisson equation with a non-zero divergence velocity field. The source term that I am working which is a cavitation source term dependent on local value of pressure.

For the most part, linearizing that source term seems to solve the issue in the literature however even with linearization my Poisson equation does not converge, and even when it does, the solution is inaccurate and often oscillatory.

Any input from the experts would be helpful

In Ansys Fluent, there is an option to solve your multiphase flow problem using either Eulerian, Mixture or VOF models. Can we analyze phase change of water to steam using VOF?

Hello,

I'm currently working on modelling multiphase flow with phase field, I'm using the PDE toolbox to simulate the phase field equation.

As described in this article: https://www.comsol.com/paper/adaptive-mesh-refinement-quantitative-computation-of-a-rising-bubble-using-comso-64111 AMR should lead to to massivley improved performance. But I'm not able to reproduce the results presented in the article. Does anyone has experience in time dependent AMR for multiphase flow in Comsol and could give me a hint what are the proper paramater in the AMR solver of COMSOL?

Thanks a lot.

Best regards,

Lukas

I benchmarked my Shan-Chen Multiphase LB model using the droplet test; further I am trying to shear deformation of the droplet under moving parallel plates (in opposite directions). I would like to plot Capillary number v/s Deformation for the validation, but I am bit skeptical about the deformation and Ca calculations and hence to check for the Re of my simulation.

Modeling multi-phase flow propagation using

**Ansys Fluent****, OpenFOAM, Flow-3D**, etc., how the force, such as**Drag force**and**Surface Tension**, apply to each of the phases?What about other forces? Do the forces such as,

**Added Mass**, and**Basset Force**apply in the all phases? How?Is there any concise reference or instruction for the modeling of multicomponent fluids?

Hello guys,

I would like to know whether I could simulate three phases or three liquids in the VOF model in Ansys Fluent. If we can, then how can we do it?

One is Air and the other two liquids are polymers. Any suggestions are highly appreciated!

Thank you

Rajesh

Hello experts, I am a new to ANSYS fluent. Currently, I am facing some issues in my problem which is on multiphase flows. I have used VOF method in Ansys fluent but during my simulation I am unable to incorporate the material properties of my inlet fluids. Can anyone help me to know the process of incorporating more than two fluids in such multiphase flow analysis in Fluent ? Here I am attaching the screenshot of the procedure of applying material properties I have been using. I am confused whether the procedure I am applying is correct.

Hi all,

The case I want to simulate includes a porous media baffle, with water on the left side and no water on the right. I want to simulate the process that water on the left flows into the porous media and then flows into the right side.

In my simulatioin, the seepage velocity (from the soil to the fluid domain) at the interface is calculated by solid part. Then, there should be more water at the interface in fluid domain. I’ve managed to couple the seepage velocity at the interface in OF, but how could I add the water due to the seepage according to the velocity at the interface? Could anyone please give me any hints?

Hello Everyone,
I am trying to simulate a Y shaped channel using VOF method in Ansys Fluent. Discretization of the model has been done. Inlet velocities of both dispersed and continuous phase are calculated using Capillary Numbers. I have considered no slip boundary condition at domain wall. Hereunder is the method I have applied while performing the simulation:
Method-
a)pressure velocity coupling scheme= coupled with vof
b) Discretization method- Green gauss cell discretization method
c) Pressure-PRESTO
d)Momentum-Second order upwind
e) Volume fraction-compressive
f) Transient formulation-Bounded second order implicit
Provided a suitable Residual of 10^-6, Time step size- 100 and Max iterations/step size-20.
My objective is to form a Janus Droplet. But droplet is forming but no janus droplet formation took place applying this methodology. Can anyone please throw a light on where I am doing wrong or is there any other process to form a Janus droplet.

I'm looking for publications regarding the Two-Relaxation Time Lattice Boltzmann Method's forcing schemes without passing through the Multi-Relaxation Time's full procedures

I'm specifically searching for the TRT implementation of Shan-Chen forcing scheme (ueq=u+tau*F/Rho)

Any contribution is highly appreciated

hi.

I have a problem in my simulation work. I use flow-3d for simulating a surface vortex with an air core in a pipe-tank system. I have been successful simulating the vortex with 1cm mesh size, but I haven't been able to see the air core. Due to this problem I had to had to use finer mesh with size of 0.6cm.

When using finer mesh ,my streamlines of the near surface particles change dramatically in comparison with the streamlines I had when using coarser mesh with 1cm mesh cell size.

In coarser mesh my streamlines are strongly sucked and driven into my pipe but when i reduce my mesh cell to 0.6cm, with exactly the same setup my streamline suddenly get shorter and incomplete. It seems that after changing the mesh size the flow of water in to the pipe is not enough strong to create the enough suction for near surface particles of water and due to this there i see no air entrainment afterward.

I will upload the photos of my streamlines in both conditions, I'll be so delightful if anyone can tell what is the cause of this problem I have and how I can solve it?

I need two model heat exhanger between air and water. But air will be admitted in liquid state at negative temperature and on leaving the heat exchanger it should be in gaseous state.

In this problem two fluids are involved

Water

Air

Once again Air has enter in

Liquid state

On transferring heat from water it has to be converted to

Vapour.

I'm aware interphasechangefoam for phase change and CHTMultiregionfoam for two fluids. But in this case two fluids are involved. In this two fluid, one fluid has to undergo phase change.

Regards

Dr. Ijaz Fazil.

Dear. all,

I performed a direct numerical simulation of multiphase flow in a porous medium (considering surface tension).

How to determine the relative permeability?

In Wikipedia, it was not mentioned which flux (inlet or outlet?), how to calculate the gradient pressure for each phase?

What if I have changing viscosity (e.g. due to the temperature)

BR,

Evgenii

Hello everyone, hope all is good.

I want to analyse multi-phase fluid flow through pipe, which software is best to do so ?

Dear All,

I have been working on multiphase flow through a complex geometry having porosity 0.25. I have patched it with oil and high-salinity brine. At the inlet I am flowing low-salinity brine. It is a pressure based, laminar, species transport without chemical reaction problem.

I am opting for a VOF steady state simulation since I wanted to pressure drop at water breakthrough and volume fraction of residual oil.

Even after 3500 iterations the solution is not converging even after using a coupled solver.

Please guide.

Thanks in advance

Dr. Shilpa Nandwani

The electrical tomography can be utilized to calculate the solid concentration or gas holdup in aqueous based multiphase flows. However, there usually exists a strong nonlinear relationship between the solid concentration and tomographic image. Is there any effective way to handle this problem?

I have this problem when i take geometry in fluent .Model Information is incompatible with incoming mesh. How to resolve it?

In my Simulation I have a Filter with a multiphase flow (Air and Oil). Now in my report the pressure drop (Area weighted Average) Static-Pressure-Mixture is higher than the total pressure drop (Air selected).

Because Total Pressure is the sum of static and dynamic pressure, the static pressure normally cannot be higher than the total. Does anybody have an explanation for that?

Hello all!

I am trying to simulate a problem where a drop deforms under the given flowing conditions of ambient fluid. I want to have a coarse grid throughout the domain, but different levels of refinement should be present near the interface. I want the mesh to be refined after every few timesteps. Is there any predefined function in Fluent to implement this or do I need to use a UDF?

I have a class project where we are vacuuming wet sand and my team wishes to know how fast the vacuum container would fill with the wet sand. I am unsure how to compute the multiphase flow because I have no experience in multiphase flow. The calculation can be fairly rough, but I don't want to use a model that simply doesn't work. I have seen there are a number of methods but cannot decide which to pursue. Some sources state mixture model to be a good fit would this be the case?

Much Appreciated,

Lucas Clapp

In air-water multiphase flow CFD simulation's it is common to use a VOF = 0.5 to track or identify the position of interface or free surface.

**I would like to know why this criteria is used and if it can always be assumed the same. Otherwise, I would like to know if volume fraction can be taken different to 0.5 and, if so, ask them about a methodology to find this volume fraction**.Below I describe a case that I am simulating in Ansys Fluent:

-Sewer pipe with Length L=6 m (aligned with the x axis), Diameter D=200 mm (8 in) and longitudinal slope So = 0.005 m/m.

-Simulation in steady state of sewer pipe considering biphasic flow air-water flow.

-Model Volume of Fluid (VOF) with implicit formulation and Open Channel's submodel.

-Boundary conditions: Inlet as mass flow rate = 26.51 kg / s; outlet = Pressure outlet. The mass flow entered is such that the ratio y / d = 0.61 (that is, occupation of 61%).

-Turbulence model: k-epsilon RNG with Enhanced Wall Treatment function (y + <5).

-Pressure-Velocity Coupling method: Coupled + Pseudotransient solver.

-Spatial discretization: Least Squared Cell Based; PRESTO!; Momentum, k and epsilon with 2nd order schemes; Volume Fraction = Compressive.

-Run Calculation: Time Step Method = Automatic with Length Scale Method = User-Specified; Length Scale = 0.064 (Hydraulic Radius); Time Scale Factor = 0.3.

To verify convergence I did the following:

* Residuals at 10-4 for all variables.

* Mass balance between input and output.

* Pressure drop between inlet and outlet.

* Velocity at Inlet and Outlet.

* VOF fraction for various orthogonal planes to the pipe at x = 0.5m, 1.0m, 1.5m, 2.0m, ..., 5.5m. I configured them as Surface report-Area Weighted Average, for the Field Variable=Volume fraction and Phase=water.

Convergence is good in terms of residuals, mass flow rate (1x10-6), drop pressure, velocity. In VOF monitors the trend also stabilizes towards values between 0.40 and 0.75.

**I know a flow profile along the pipe. In my initial simulation with refined mesh, with elements of 0.02mx0.005mx0.003m, [this is (dx) (dy) (dz)], I noticed that the theoretical profile is closer when I choose VOF = 0.7 and not VOF = 0.5 as is usual in the practice.**

**From the above my doubt arises about the VOF fraction to choose.**

Thanks!

Hello everyone;

I m trying to model the mixing of

**two miscible liquids**inside a circular tank by using Ansys-fluent and i m confused which model of multiphase flow i have to use to model such case**(VOF-Mixture or Eulerian).**Best regards and thanks.

In the first case (single phase case) liquid enters the tube and absorbs heat energy which is produced by the solid region. There is no phase change happening here. The following UDF is used to calculate the source term in single phase flow. The UDF works correctly.

#include "udf.h"

DEFINE_EXECUTE_AT_END(s_calculation)

{

Domain *d=Get_Domain(1);

int zone_id=6;

Thread *t = Lookup_Thread(d,zone_id);

cell_t c;

thread_loop_c(t,d)

{

begin_c_loop(c,t)

{

C_UDMI(c,t,0)=C_T(c,t)*0.25;

}

end_c_loop(c,t)

}

}

DEFINE_SOURCE(energy, c, t, dS, eqn)

{

real x[ND_ND];

real source;

source =1680000*C_UDMI(c,t,0);

dS[eqn] = 0;

return source;

}

In second case, liquid enters the tube and undergoes phase change due heat addition.

**How to rewrite above UDF for this multiphase case.**

I am currently studying about non isothermal multiphase flows and I want to model with non isothermal lattice Boltzmann methods. Any relevant input is always welcomed. Thank you!

I am trying to simulate pyrolysis of biomass in different reactors and I have been using multiphase flow capabilities on top of conjugate heat transfer, species transport and laminar flow. I want to know more about the steps in Fluent to include multiple reaction pathways and being able to include more complicated kinetics in the simulation.

Thanks in advanced!

We are doing RTD study (pulse input method) for the flow through a packed bed in case of single phase (water) as well as air-water multiphase flow. We are facing problem about the experimental result of the Peclet number calculation, sometimes it increases with increasing velocity of the phases and sometimes it decreases. Now, my question is what would be the actual trend of Peclet number when the velocity of water increases for single phase flow and when the velocity of air increases (water inlet velocity fixed) for the multiphase flow? Please help me with the answer if you have any idea about the problem.

Hello all,

I am trying to study a very simple case of bubble rise ( air in water) using Phase field method in COMSOL. However, again and again I get this error " fFailed to find consistent initial values.

Last time step is not converged."

I see that there is some scaling setting that needs to be done. However, just to see of things work well, I took the exact parameters as given in example of capillary filling.

The only difference in my case is that I try to study the rise of bubble instead of capillary filling.

While the given example worked well, changing the boundary conditions and physics lead to an error mentioned above.

May some one help in this regard, please? How to deal with this issue. I looked across but not much was found.

Thanks

What's the meaning of the capillary entry pressure (Pd or Pe) in Brooks Corey model giving the capillary pressure as function of a fluid saturation Pc=Pd*S^(-1/lambda) and how it can be determined for a binary immiscible flow in porous media?

I got one really good paper on

**, in which they have used***"Two phase modelling in ANSYS FLUENT"***UDF**and linked them to Governing differential equations of**VOF**Model in ANSYS FLUENT. The Paper I have attached below, in which terms to be added as source term is also given.I am going through UDF manual of ANSYS FLUENT and all the materials that I have with me for

**understanding how to link the source terms though UDF with the Governing differential equation of VOF model.**If you have any program written in C for adding the source term to governing differential equation of VOF model,

**please share your inputs on this topic**Thanks regards,

Somnath Rangrej

Mail ID: rangrej.somnath@learner.manipal.edu

Dear all,

I am modelling a drying process using a Eulerian multiphase flow in Fluent. The rate of evaporation of water-liquid is changing depending on the volume fraction of water liquid in the porous media. Therefore, to calculate the mass transfer I should write a udf which calculate the mass transfer according to the volume fraction which is provided in each time step. When searching in udf guide, I face C_VOF for this but it is mentioned that this can be used to get volume fraction in VOF multiphase model. I will really appreciate if anyone help me how i can get the volume fraction in each timestep in Eulerian model.

Thank you in advance,

Elham

I am currently doing a gas-liquid phase change simulation, but the false phase change near the gas-liquid interface occurs due to the spurious velocity. Is there any way to reduce or eliminate this non-physical phenomenon?

Thanks for your help

We all know that VOF method in multiphase flow is conservative...

when using this with method in free surface or interfacial flow we ended with mass loss even with a a finest grid, is there any way to conserve the overall mass of liquid ?

We want to apply the solid surface by Shao et al. 2014 model [Free-energy-based lattice Boltzmann model for the simulation of multiphase flows with density contrast].

How can terms of density, chemical potential and order parameter gradient for solid surface be defined?

Dear Fellow colleagues,

I'm trying to simulate a metallic powder flow under the effects of gravity only in a circular tube in 2D. I'm using the eulerian multiphase model, fluent doesn't seem to like that the density of the secondary phase (the powder phase which is 5500 kg/m3) is higher than the density of the primarty phase (air), up to 5-8 kg/m3, there's no divergence but higher than that, the divergence starts from the early iterations!

Any advices on how to solve that?

Thank you in advance

Karim ZAYNI

If so, why are they defined as "suspensions" in the majority of literature, including high-ranked journals?

Although both are heterogeneous two-phase systems, as far as I know, in suspensions, particles settle on standing. While in colloids, the solid phase remains dispersed and does not separate on standing.

I am no expert, but this truly confuses me. Am I missing something?

Your feedback is appreciated!

how to add a wall flux boundary condition of the primary species onlu?

I am using Fluent for simulating multiphase flow (gas-liquid) inside micro channels (0.1-16 microns). I have a problem in making water (as wetting fluid/hydrophilic) flowing as a film on the insid the wall of the channel. Please could anyone help with this one?

I have simulated a multiphase flow in Ansys fluent and now want to transfer the pressure load from the fluent to the ansys mechanical to do a fluid structure interaction.

If so, how can we define the Knudsen number for solid nanoparticles dispersed in a liquid carrier? And how can the mean free path of liquid molecules be calculated?

Conventionally, Knudesn number is used in the framework of the kinetic theory of gases to judge the levels of gas rarefaction and slip-boundary effects. Is the same concept somehow applicable to particulate flows (such as nanofluid flows) with a liquid carrier phase?

Please note that in my approach, the particle phase is already treated from a discrete perspective and only the fluid phase is treated as a continuum. Therefore, my purpose is to judge if this treatment of the fluid phase is correct.

Also please note that I am aware of the popular use in the nanofluid literature of a Kundsen number defined as MFP/D, where MFP if the mean free path of the liquid molecules (?) and D is the nanoparticle diameter. However, I am not sure about the applicability of this criterion for treating the fluid phase as a continuum in a particulate flow system.

Your feedback is much appreciated.

maybe the small amount of the DataSource

How can we calculate capillary pressure in multiphase flow system in a porous reservoir with relative permeability and saturation as the given values. What I require is data on capillary pressure with change in relative permeability of gas or water saturation. This is in context of CO

_{2}sequestration in deep saline aquifers.What are the differences between capillary pressure and interfacial tension in the context of multiphase flow in porous media? I understand that capillary pressure is the pressure at the interface between two phases in contact. Then what precisely is the interfacial tension?

Hi

I am simulating a kind of electrolyzer in Fluent. Consider a 2D-box, the bottom boundary is opening, top boundary is degassing, gas is generated from a part of left side boundary and right boundary is wall. I did the mesh dependency test and got dy=1mm is an optimum size. Now, if I set the vertical size of cells close to the degassing boundary equal to 1mm the total amount of gas in the domain will be A%. But, if I change the cell size close to the degassing boundary to a smaller value (e.g. dy= 0.5mm) then the total amount of gas in the domain in the steady-state condition will change. Note that I only change the cell size close to the degassing boundary to see the effect of cell size of the performance of the degassing boundary.

I know that Fluent specifies a mass sink for the gas phase in the cells adjacent to the degassing outlet which is related to the cell size (i.e. mass sink=integral (e_g * rho_g* u_n*dA) ), but I do not know how I can get similar results with degassing boundary when changing the cell size. any idea?

I need to compare results for a simulation with nanofluids in a coiled tube using the single-phase and two-phase methods in FLUENT. The single-phase method works perfectly well. However, I am confused with the development of the two-phase Mixture model. The pertinent literature states that the fluid properties need to be defined through the use of the effective properties (as in the single-phase simulations). Hence, I am not sure on how to define the model in FLUENT.

Therefore, if we define the mixture with two phases, my understanding is that the base fluid properties (water) will be defined with the UDFs for the effective nanofluid properties. Then how can we define the properties of the nanoparticles i.e. the second phase?

Am I right to assume that for the second phase, the granular option needs to be activated?

Hello all

I am simulating hydrogen generation in an electrolyzer compartment using Eulerian model in Fluent. The final amount of gas in the domain when the solution reaches steady-state condition is about 25% and 14% for Explicit and implicit solvers respectively. What is the reason for this difference? I have checked even very small values for the time-interval to see if two solutions become similar, but they did not. Any idea about the reason for this difference between the results? How can I get similar results?

The multi-phase fluids are widely used for annular hole cleaning, but I am not sure what advantages do they offer compared to single-phase fluids in overall removal of cuttings for the annulus.

How can we model multiphase flow of DEM (discrete element modelling) and SPH (smooth particle hydrodynamics)/ lattice boltzman method using comsol. Also if there is any other good software to perform similar problem

Hi,

I am simulating a multiphase flow through a geometry having a cylindrical passage then nozzle then an orifice. I am interested in calculating the Reynolds number. I have gone through few literature. Different people have used different correlation. I am not sure which one to use? some people have used Re= 4mtotal/pi*Do*muavg

Where Do is the exit dia. M total is the total mass flow rate which includes both the phases.

mu avg is the mass average coefficient viscosity

Some people has used Re = rhol*Va*D/mul

where rhol ,mul are liquid property and Va is the gas velocity

Both the correlation is giving me pole apart results. Kindly suggest me the proper one.

Hello everyone,

I want to simulate a multiphase - flow (eulerian - eulerian) through a porous media in Ansys Fluent without the effect of diameter. In the eulerian model, by default only drag is active for the phase interaction between the two phases. So the effect of diameter should no more be present, if I disable drag. If I disable drag (from schiller-naumann to none), my simulation gets unstable and I get the message "floating point exception". Can anyone help what I can do, or give me an alternative to delete the effect of diameter in my simulation?

Dear All,

Greetings.

I would appreciate it if anyone can recommend a book (or any other related reference) for miscible multiphase displacement flow especially if it is for Non-Newtonian fluids in Oil well cementation.

Thanks in advance.

Best Regards.

I have a thin porous material whose saturation needs to be determined. The relative permeability for a multi-phase flow is to be determined through the porous material and in order to express relative permeability as a function of saturation, I need to determine the saturation. The sample is of the dimension of 10mmX5mm and thickness of approximately 500 microns. How can I effectively measure the water saturation. Also, I think the internal methods of saturation determination like X-Ray method, neutron scattering would be not very effective considering the small dimensions of the sample. Correct me if I'm wrong.

In a case where there is a multiphase flow through a heating pipe (heat flux is provided), if I use (say 0.3kg/s) mass flow rate as tube inlet boundary condition at a known temperature, can I use same mass flow rate (0.3kg/s) as tube outlet boundary condition?

Or will there be change in mass flow rate at outlet.

Actually, I need the BC at outlet to be like 'Outflow' (as we use it in Fluent). I don't know the property of fluids at outlet. Rather, it is what which is to be find out (like temperature, vol. fraction, etc.).

Also, how can I allow backflow (if needed) around outlet?

In 'Opening' type BC, I do not understand how I can specify Opening Pressure and Temperature if they are yet to be calculated by the solver?

Thank You.

Hi guys,

I recently ran into a paper simulating pore-scale porous media with FVM-VOF model and then validated it with another numerical approach based on LBM named Shan-Chen LBM model and received more or less the same results; however, it did not mention anything about the pros and cons of these two approaches except that LBM is more flexible in dealing with complex geometries and boundary conditions than traditional FVM-VOF.

Has anyone got any clear idea and explanation of the difference between these two approaches, e.g, computational time or accuracy in capturing interface, etc?

Any helps or comments would be appreciated in advance

Why does the imbibition process need a much higher pressure than the drainage process in the two-phase fluid flow in porous media?

Principally, because capillary pressure plays a positive role to drive the flow of wetting phase (e.g., water), the flow in an imbibition process (e.g., water displacing oil) should be easier (less pressure cost) than in a drainage (e.g., oil displacing water) process.

However, as shown by many laboratory core-scale test results, an imbibition usually needs a much higher pressure (e.g., 100 kPa) to drive the flow than a drainage (e.g., 20 kPa) under the same injection rate (e.g., 0.5 mL/min).

The high pressure during imbibition should be not due to the viscosity difference between fluids. When injecting either one of the phases alone in the media, the pressure drop is quite low.

Hallo fellow Researchers,

I need to update my knowledge on Multiphase Flows and Fluidization processes. Especially with Continuum and Kinetic Theory Descriptions.

In 1994 Prof. Dimitri Gidaspow issued a great book: https://www.elsevier.com/books/multiphase-flow-and-fluidization/gidaspow/978-0-08-051226-6

Does anyone know if something changed about understanding the Continuum and Kinetics during last 20 years?

Are there some newer books with updated data or Gidaspow's work is complete for now?

Thanks in advance and Best Regards,

Stan

Hello all,

May some one suggest references wherein some relation has been proposed ( and proved ) between grid size and cahn-number.

In my understanding, it is known that one should consider about 3 grid points ( minimum as proposed by Jacqmin) in the interface.

Well then as per that relation, Cn= int_thickness/L ( L being characteristic length of the domain).

Thus, we have Cn= 3*grid_size/L . But is this correct. I read somewhere ( can't remember where) that its best to have grid size varying from Cn-Cn/4.

May some one help in this regard.

Thanks

What are the recent advancements to dissolve hydrogen in water?

I couldn't find any recent (2014-2015) articles on dissolving hydrogen in water. It would be great if someone could help me in this regard.

Is someone aware of a method for simulating embedded boundaries on a Cartesian grid (cut-cell or IB) which conserves mass exactly in volume-of fluid framework for the direct numerical simulation of multiphase flows?

I am modeling multiphase flow and i counter this error:
In Analysis 'Flow Analysis 1' - Domain 'fluid': The following materials require Viscosity to be defined: 'Aluminium'

i try to use alminium as my dispresd solid phase and water as my countinus phase.
How can i solve this error?

Currently, the fluid drop impact on solid walls is an important research area in the scientific community. The droplet spreads out on the wall after impact. In some cases, the tip of the spreading lamella levitates and travels along the surface without touching the wall. Quite interestingly, this is observed in drop impact on both hydrophobic and hydrophilic surfaces. What are the main reasons for this phenomena? How can we categorize them?

The image is from

Article Drop Impact on a Solid Surface

Hi,

I am trying to renovate old laboratory apparatus for the study of the hydrodynamics of countercurrent liquid-liquid flow through a packed column. Not for research, but rather education and didactics, as part of general course on various aspects of basic unit processes (Chemical Engineering lab).

While it was once operated using water and tetrachloromethane, since that time new legal regulations were introduced and the former was deemed too toxic to use in such configuration (it isn't standing in the fume hood and is rather impossible to move it there). New question arose - whether replace this apparatus with something else,, or maybe just change the second liquid. We have quite a bit of ideas, but I decided it wouldn't be bad if I will also move the discussion here, and maybe somebody will catch up.

After that general introduction to a topic, the final question is just the same as above: can anyone recommend some non-toxic liquid, that is not miscible with water in considerable proportions and with comparable dynamic viscosity (or just quite low)?

I am open to various suggestions.

PS.

We thought about, for example, some kind of vegetable oil as non-polar phase, as they are cheap and readily available. However, they are also quite viscous in comparison with water and prone to ageing. While first isn't big problem, we could just buy the pump well-adjusted for handling oils, the second issue is quite a nuisance.

I am trying to simulate the gap resonance between two floating bodies and with a gap of 3m under the effects of ocean wave (direction longitudinal of the ships body) . I am trying to put surge, sway and yaw as fixed. There should be a damping effect on floating bodies due to viscous effect and radiation . How do I determine the linear and damping coefficient of such bodies. This is my first time simulating a multiphase flow and needed advice on this.

As in multiphase flow it is said that surface tension plays a role in mini channels rather than gravity, I am unable to understand, is there any mathematical equation that supports or experimental study?

Some thermodynamics confusion.

Assume ideal gases for simplicity.

Are kinetic energy (K) and internal energy (U) for gases, different from one another? As I understand,

dU = n C

_{v }dtAnd if some work is done by a gas adiabatically, then

heat change dQ = 0

Now we can have two cases:

1) Expansion occurs at the cost of internal energy of the gas and so gas temperature falls as the gas expands. So, U decreases.

Or,

2) As the temperature falls, the velocity of the gas molecules deceases too which then consecutively lowers the K of the gas.

So, are K and U the same physical quantity? Do they imply the same physical parameter of a system or something different? Or, may be both K and U undergo change in such a process?

Another issue is if work (classically) done = P V

then dW = P dV is seen more often. I am aware that W is not an exact differential, still shouldn't it be dW = P dV + V dP, as one can intuitively guess that during an adiabatic expansion of a gas, as volume increases, pressure will change (fall?) too? Why V dP is often left out?

Any comment will be appreciated.

I am working on a multiphase flow through a porous medium. in my system I am introducing water at a constant flow rate in a porous medium filled with oil. There is outflow only when pressure in the system has exceeded 400 psi. please help me in how to put this condition in gambit.

Thanks.

Regards,

Shilpa Nandwani

which is better for temp measurement of fluid flowing inside tube in upward direction. there are an options by use thermocouples or PT100, which way is more acceptable for such case? I hope to hear from you if any one have an experience. for information the flow is multiphase flow.