[openfoammaofnepo]

Hi All,

I read the pEqn.H in twoPhaseEulerFoam and have some questions. The openFOAM version is 3.0.0.

https://github.com/OpenFOAM/OpenFOAM...Foam/pU/pEqn.H

1, in lines 132 and 141, there are the following source code lines:

- alphaf2*fvc::interpolate(rho1 - rho2)*(g & mesh.Sf())

- alphaf1*fvc::interpolate(rho2 - rho1)*(g & mesh.Sf())

What do the above lines mean physically?

2, the pressure "diffusivity" is constructed in line 215, this can be understood since finally the pressure equation has the term of \nabla (\Gamma \nabla p). \Gamma is the "diffusivity", and is predicted with

mag(alphaf1*alpharAUf1 + alphaf2*alpharAUf2)

If I am not making a mistake, the pressure "diffusivity" should be: alpha_1/(rho_1*A_1) + alpha_2/(rho_2*A_2). Here A_1 and A2 are the diagonal part of the coefficient matrices from momentum equations. alphaf1 and alphaf2 are computed at the very beginnig of pEqn.h file, while alpharAUf1 and alpharAUf1 are coputed by lines25-32. This equation is not consistent with the above code, is it?

3, Could anybody give some hints about what is the following lines doing? What does pEqnComp1 stand for?

        pEqnComp1 =
            (
                contErr1
              - fvc::Sp(fvc::ddt(alpha1) + fvc::div(alphaPhi1), rho1)
            )/rho1
          + (alpha1*psi1/rho1)*correction(fvm::ddt(p_rgh));

4, I found the governing equation of pressure is solved starting by the following:

        solve
        (
            pEqnComp1() + pEqnComp2() + pEqnIncomp,
            mesh.solver(p_rgh.select(pimple.finalInnerIter()))
        );

However, the above lines are within the while loop:

while (pimple.correctNonOrthogonal())
{....

}

So if in the system/fvSolution, we set nNonOrthogonalCorrectors 0;. Does it mean actually the lines within the while loop and therefore solving the pressure will not be executed?

Thank you so much for your help.

OFFO

[nic92]

Any answer? I have similar doubts.
Thanks in advance.

[openfoammaofnepo]

Dear Gerhard,

In the twoPhaseEulerFoam, do you have experience to include the radiation model for both phases or for the primary phase? I am considering the possibility of this and need to decide how to proceed. If you have some comments about it, I would really appreciate it.

Thank you so much.

[openfoammaofnepo]

I am using reactingTwoPhaseEulerFoam for simulating particle-laden gas flows with chemical reaction. The Openfoam version is 3.0.1. In this solver, the UEqn, heEqn and YiEqn are written in source files for phaseModel, i.e.

UEqn ---> MovingPhaseModel.C
YiEqn ---> MultiComponentPhaseModel.C
heEqn ---> AnisothermalPhaseModel.C

So when the solver is running, these functions will be called, and then momentum, energy and species mass fraction equations are constructed. In the /phaseModel, there are many classes for phaseModel, however, each model is inherited from BasePhaseModel in a public way. So, what are the relations between these classes for phaseModel in the folder /phaseModel? They are completely parallel, or they are inherited from some others in this folder? Not clear for me now. Anybody knows?

Thanks.

[hooman.4028]

Originally Posted by GerhardHolzinger

You find an answer to your question by playing around.
There is a tutorial case of twoPhaseEulerFoam, named injection, which uses the fvOption framework.

If you run the tutorial as is, then the solver tells you about the active fvOptions models. See the relevant lines of solver output below.

No MRF models present

Creating finite volume options from "constant/fvOptions"

Selecting finite volume options model type scalarSemiImplicitSource
    Source: massSource1
    - selecting cells using points
    - selected 1 cell(s) with volume 8e-06
Selecting finite volume options model type vectorSemiImplicitSource
    Source: momentumSource1
    - selecting cells using points
    - selected 1 cell(s) with volume 8e-06
Selecting finite volume options model type scalarSemiImplicitSource
    Source: energySource1
    - selecting cells using points
    - selected 1 cell(s) with volume 8e-06
Courant Number mean: 0 max: 0
Max Ur Courant Number = 0
Calculating field DDtU1 and DDtU2


Starting time loop

Then, I renamed the file fvOptions, any name other than fvOptions does the trick. With a non-present fvOptions file, the solver output looked like this:

No MRF models present

No finite volume options present

Courant Number mean: 0 max: 0
Max Ur Courant Number = 0
Calculating field DDtU1 and DDtU2


Starting time loop

Hello Gerhard,

Thank you for the tutorial. I had a question, what are phasePressureCoeffs? I have been through so many different documents but no luck yet. For example, if the g0 is found via SinclairJackson, then what is the point of defining a new constant for it? The default is 1000. How do we calculate this?

Thank you,

[masimasiqi]

Originally Posted by openfoammaofnepo

Hi,

In twoPhaseEulerFoam, is it possible to print out the residual and number of the iterations for the momentum equations as well? In stead of just say: 'Constructing momentum equations'. Since I should know the residuals of solving the momentum equations. In the current solver of twoPhaseEulerFoam, we can get as follows:

==========
PIMPLE: iteration 1
MULES: Solving for alpha.particles
MULES: Solving for alpha.particles
alpha.particles volume fraction = 0 Min(alpha.particles) = 0 Max(alpha.particles) = 2.4e-05
Constructing momentum equations
min T.particles 300
min T.air 300
GAMG: Solving for p_rgh, Initial residual = 1, Final residual = 6.98034e-09, No Iterations 22
==========

Thank you so much.

Heyyy, I have the same questions about the residuals of momentum equation. Have you get the residuals and iterations of alpha or velocity?



It seems that the momentum equation is not solved... only used as a Momentumpredictor before PIMPLE loop to deal with pressure and velocity coupling...



thanks a lot

[qi.yang@polimi.it]

Hi guys, I have a question that after I changed the twophasesystem.C and compiled it, as the Make/files like "LIB = $(FOAM_USER_LIBBIN)/libmycompressibleTwoPhaseSystem". I include this code in system/controDict. However, the solver neglected it and still used the original twophasesystem.C. If I Make/files like "LIB = $(FOAM_LIBBIN)/libcompressibleTwoPhaseSystem", it surely works. I need to make it into user's library. Do you have any suggestion? Thanks a lot.

[Jasper Z]

Dear openfoammaofnepo,

Hope all is well! I know this thread is long time ago, but I am also confused with the pressure "diffusivity" in twoPhaseEulerFoam. It should be exactly what you wrote: alpha_1/(rho_1*A_1) + alpha_2/(rho_2*A_2), but the code reads, mag(alphaf1*alpharAUf1 + alphaf2*alpharAUf2), where alpharAUf1 is defined as alpha1f*A_1, which is not consistent with the equation, have you managed this question?

Kind regards,
Jasper

[oscar_zagal]

Hi dear all

I saw that knowing the entire code of this solver is very difficult, my question is: why don't the creators of the solver post a description of the goberning equations and other stuff like the pressure diffusivity?

I know that OpenFOAM is free, but at least a brief description would be very nice.