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Implicit solver for gamma volumefraction equation

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Old   July 8, 2009, 03:35
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isabel
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I only have advisors this week. I am at a OpenFOAM course, which finishes on Friday.

fv::gaussConvectionScheme<scalar>(mesh, phi, UDs).fvmDiv(phi, psi),

This line is to calculate div(phi, psi). The begining is only to specify to the program how to calculate it.

And the div(U) is repeated.
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Old   July 8, 2009, 04:36
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Sandy Lee
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Wow, it is great. Thank you very much.

By the way, what a OF course are you studying? Do you have some documents or websites to share?

Sandy
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Old   November 5, 2009, 04:31
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Hi, everybody, I am trying to use the interPhaseChangeFoam in OpenFOAM-1.6, and just meet the same problem how to set MULES::implicit in the fvSolution file. Any suggestions are appreciated.

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Old   November 5, 2009, 19:48
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Sandy Lee
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Hi Chiven, is there the tutorial about InterPhaseChangeFoam in OF-1.6? I use the OF-1.5.

-------------------------------------
gamma MULESImplicit
{
maxIter 1000;
nLimiterIter 10;
maxUnboundedness 1;
CoCoeff 0.2;
solver PBiCG
{
preconditioner DILU;
tolerance 1e-10;
relTol 0;
};
};


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Old   November 5, 2009, 20:23
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Hi, Sandy, thanks for your reply.

I have justed used the similar setting like yours, but failed. At this time, I have NOT run the interPhaseChangeFoam successfully in OpenFOAM-1.6.

Code:
    alpha1
    {
        MULESImplicit
        {
        maxIter 1000;
        nLimiterIter 10;
        maxUnboundedness 1;
        CoCoeff 0.2;
            solver PBiCG
            {
            preconditioner DILU;
            tolerance 1e-10;
            relTol 0;
            }
        }
    }
Best regards,
Chiven



Quote:
Originally Posted by sandy View Post
Hi Chiven, is there the tutorial about InterPhaseChangeFoam in OF-1.6? I use the OF-1.5.

-------------------------------------
gamma MULESImplicit
{
maxIter 1000;
nLimiterIter 10;
maxUnboundedness 1;
CoCoeff 0.2;
solver PBiCG
{
preconditioner DILU;
tolerance 1e-10;
relTol 0;
};
};
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Old   March 29, 2010, 13:20
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Suresh kumar Kannan
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Hello
I am planning to modify the interfoam solver of OF-1.6.x with the implcitMULES and use an LES simulation. I am studying the breakup of 2D liquid sheets. I have already run some simulations in which i see that the solution is very much dependent in the CFL number

I want to know th experience of other interFOAM users who have used an implicitMULES. Do you really find a difference in the solution of two explicitMULES and implicitMULES. And if yes what was the improvement. Is it advicable to give the implicitMULES a try. Will it allow me to use higher CFL numbers.

bye
with regards
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Old   April 8, 2010, 05:08
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Suresh kumar Kannan
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Hello interFoam and interphasechange users,

I implemented the implicit::MULES in interFoam in OF-1.6.x . Thanks to Niels and pbohorquez.and ran it with the LES model on some preliminary test cases. I can already see that the results are much better than the explicit::MULES case.
So i have decided to further look into the implicit::MULES solver. I already read the posts in this discussion. That gave me a good idea about the form of the equation that is being solved in the two cases.

But I would like to know more about the discretization of the transport equation when i am using an implicit::MULES, because i really dont get anything about the parameters that i specify in the fvSolution

gamma PBiCG
{
MULESImplicit
{
maxIter 1000;
nLimiterIter 10;
maxUnboundedness 1;
CoCoeff 0.2;
}
preconditioner DILU;
tolerance 1e-06;
relTol 0;
};

so it would be very useful to me if anybody gives some explanation about the discretization in the case of MULES implicit.

with regards
K.Suresh kumar
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Old   July 14, 2010, 12:25
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Nima Samkhaniani
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hi friend
the correct form of alpha fvSolution is like below :
alpha1 MULESImplicit
{
maxIter 1000;
nLimiterIter 10;
maxUnboundedness 1;
CoCoeff 0.2;
solver PBiCG;
preconditioner DILU;
tolerance 1e-06;
relTol 0;
};
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Old   June 17, 2011, 16:18
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Quote:
Originally Posted by sandy View Post
==================================

Hi, it seems that you lost the compressible term: div(gamma*(1-gamma)*phi). I guess the gamma equation should be as follows:

d(rho*gamma)/dt + div(phi*gamma) + div(gamma*(1-gamma)*phi) - Sp*gamma - Su = 0
Hi Sandy,

In order to strictly restrict alpha in [0,0.52], I am now considering to use MULES in case of bubbly flow. I have a question here since in Weller's scheme, there is a compression term (eqn 4.13, Rusche). And it is said "The arti ficial term is only active in the thin interface region because of the multiplication term gamma(1-gamma)". It is true in case of liquid-vapor with clear interface which only exists somewhere. However in bubbly flow, the interface could be everywhere. I dont know if it is appropriate to use this scheme in my case. Thanks.

// Kai
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Old   June 27, 2011, 20:11
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Sandy Lee
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You can try them, respectively. I guess, there are not differences in results but in the performance of convergence ...
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Old   July 14, 2011, 04:08
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Pablo
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Hello Suresh,

What are the steps to update interfoam from mules::explicit to mules::implicit??

Advanced thanks,

Pablo
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Old   July 14, 2011, 05:01
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Anton Kidess
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Pablo, simply replace the call to MULES::explicitSolve in alphaEqn.H to MULES::implicitSolve and recompile. You will need some extra entries in the fvSolution file as shown in a post earlier in this thread, and that's it.
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Old   July 14, 2011, 12:47
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Thanks Anton,

It is working, i copied from interphase tutorial;

alpha1
{
maxUnboundedness 1e-5;
CoCoeff 2;
maxIter 5;
nLimiterIter 2;

solver PBiCG;
preconditioner DILU;
tolerance 1e-12;
relTol 0.1;
};

but what mean cocoeff,maxiter and nlimiter??
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Old   March 27, 2012, 22:11
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Hello all

Could any one share this file with me:
OpenCFD, OpenCFD Technical report no. TR/HGW/02 (unpublished); 2005

Regards
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Old   June 25, 2012, 21:41
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Quote:
Originally Posted by sandy View Post
==================================

Hi, it seems that you lost the compressible term: div(gamma*(1-gamma)*phi). I guess the gamma equation should be as follows:

d(rho*gamma)/dt + div(phi*gamma) + div(gamma*(1-gamma)*phi) - Sp*gamma - Su = 0

In MULESTemplates.C,
phiPsi = phiGamma = phi*gamma + gamma*(1-gamma)*phi

is it right? If that, in gammaEqu.H, why Su = divU*gamma + vDotcAlphal ? It look like that the term divU*gamma was repeatedly solved ??

I knew, to the gamma transport equation,
Source term = vDotvAlphal * gamma + (1 - gamma) * vDotcAlphal = (vDotvAlphal - vDotcAlphal) * gamma + vDotcAlphal.
So, Sp = (vDotvAlphal - vDotcAlphal) * gamma , and it will be solved implicitly.
Su = vDotcAlphal, and it is an explicit term in this equation.

but again, why Su also includes the term divU*gamma in gammaEqu.H ? If the MULES::implicitSolver was chose, this term should be deleted, right?
hello, Sandy. I have some question about the source item in interPhaseChangeFoam. In this Solver, vDotcAlphal = vDotvAlphal * gamma + (1 - gamma) * vDotcAlphal = (m+ + m-)*(1/rho1 - alpha(1/rho1 -1/rho2)). I doesn't understand why it is (1/rho1 - alpha(1/rho1 - 1/rho2). I think it should be source = (m+ + m-)/rho1.
So, can you give me some suggestion?
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Old   June 25, 2012, 22:16
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Sandy Lee
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Hi, why you not read some papers by Dr. Lu Naixian and deduce those equations?
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Old   March 27, 2014, 13:02
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Hi,

I think, it is not as trivial as you suggest in a not very friendly way. In addition, it is link to a query often ask in this forum and As far as I have searched I did not find an answer.

If someone have any interrest on this, in can give some suggestion.

Bye
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Old   November 7, 2014, 18:20
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Quote:
Originally Posted by nygbook View Post
hello, Sandy. I have some question about the source item in interPhaseChangeFoam. In this Solver, vDotcAlphal = vDotvAlphal * gamma + (1 - gamma) * vDotcAlphal = (m+ + m-)*(1/rho1 - alpha(1/rho1 -1/rho2)). I doesn't understand why it is (1/rho1 - alpha(1/rho1 - 1/rho2). I think it should be source = (m+ + m-)/rho1.
So, can you give me some suggestion?
Hi,

I'm also confused. Have you been successful in finding why the volumetric source is formulated with this coefficient? It is the same as rho_mixture / (rho_1 * rho_2).
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Old   July 11, 2015, 04:59
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Quote:
hello, Sandy. I have some question about the source item in interPhaseChangeFoam. In this Solver, vDotcAlphal = vDotvAlphal * gamma + (1 - gamma) * vDotcAlphal = (m+ + m-)*(1/rho1 - alpha(1/rho1 -1/rho2)). I doesn't understand why it is (1/rho1 - alpha(1/rho1 - 1/rho2). I think it should be source = (m+ + m-)/rho1.
Hi nygbook
You can find an answer in Jibran Heider master thesis in chapter 2.1

http://www.cimne.com/cvdata/cntr2/sp...branHaider.pdf
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