[venkataramana]

Dear Foamers,
I am unable to understand the code given in the RhoCentralFoam.C i mean the working procedure, but in the user guide given about pisoFoam and IcoFoam. Where should I find the information about the code like " reconstruct(rho)"

thanks in advance.

[alberto]

There is a paper on the solver:

Christopher J. Greenshields, Henry G. Weller, Luca Gasparini and Jason M. Reese, Implementation of semi-discrete, non-staggered central schemes in a colocated, polyhedral, finite volume framework, for high-speed viscous flows, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Int. J. Numer. Meth. Fluids 2010; 63:1–21

For the definition of reconstruct: ~/OpenFOAM/OpenFOAM-2.0.x/src/finiteVolume/finiteVolume/fvc/

I hope this helps.

[venkataramana]

Dear Alberto Passalacqua thank you very much for your kind information

Regards,

[buaawangwei]

Hi alberto,
I want to know that rhoCentralFoam is a steady solver or a transient solver?Thank you

[alberto]

It is a transient solver. You can check that easily by looking at the tutorials.

[nsreddysrsit]

There are two types of solvers in openFoam for compressible flows. For example RhoSimpleFoam and RhoCentralFoam. The solution methods (algorithm) are different for the above two solvers. How to choose the solver. And what are all the parameters we have to consider while selecting the solvers.

Regards,

[alberto]

Originally Posted by nsreddysrsit

There are two types of solvers in openFoam for compressible flows. For example RhoSimpleFoam and RhoCentralFoam. The solution methods (algorithm) are different for the above two solvers. How to choose the solver. And what are all the parameters we have to consider while selecting the solvers.

Regards,

The rhoSimpleFoam solver is a pressure-based solver for steady state laminar and turbulent (RAS) flows. An unsteady version is available in rhoPimpleFoam.

The rhoCentralFoam solver uses a density-based approach with central schemes, and it solves the unsteady equations.

The choice of the solver depends on the type of flow you have:

- Steady/unsteady?
- High Mach number (density based approach) / low Mach number (pressure-based approach)?

Best,

[nsreddysrsit]

hi alberto,
Thanks for reply,

How to find the which solver is the best for different range of Mach Numbers, and is there any limitation for any solver for prescribed Mach Mumber, How to find that. How the results are varies if i use pressure based solvers and density based solvers if i use same problem. what are all the factors we have to consider.

Regards,

[alberto]

Originally Posted by nsreddysrsit

hi alberto,
Thanks for reply,

How to find the which solver is the best for different range of Mach Numbers, and is there any limitation for any solver for prescribed Mach Mumber, How to find that. How the results are varies if i use pressure based solvers and density based solvers if i use same problem. what are all the factors we have to consider.

Regards,

I think you should really refer to the literature to understand the limitations of each approach, since special formulations of each of them are available and aim at extending their range of applicability.

If you have a specific problem in mind, you should provide details about it, so that the question is specific.

[sahas]

Originally Posted by nsreddysrsit

How to find the which solver is the best for different range of Mach Numbers, and is there any limitation for any solver for prescribed Mach Mumber

Hallo!
I am using rhoCentralFoam for my transsonic laminar problem. May be I am wrong, but the one of the main feature of rhoCentralFoam I think is using of fully conservative scheme, so the main conservative laws (for example, for energy) are always preserved. I tried sonicFoam and rhoSimpleFoam and found that there were problems with temperature distributions (such problems were discussed on the forum).

As for rhoPimpleFoam I cannot get it worked for my case =(

So I recommend use of rhoCentralFoam for the problems with Mach number > ~1

[immortality]

Hi
what does the lines for momentum solving in this solver mean?

// --- Solve momentum
        solve(fvm::ddt(rhoU) + fvc::div(phiUp));

        U.dimensionedInternalField() =
            rhoU.dimensionedInternalField()
           /rho.dimensionedInternalField();
        U.correctBoundaryConditions();
        rhoU.boundaryField() = rho.boundaryField()*U.boundaryField();

        volScalarField rhoBydt(rho/runTime.deltaT());

        if (!inviscid)
        {
            solve
            (
                fvm::ddt(rho, U) - fvc::ddt(rho, U)
              - fvm::laplacian(muEff, U)
              - fvc::div(tauMC)
            );
            rhoU = rho*U;
        }

whats the mathematical(CFD)form of the equation:

fvm::ddt(rho, U) - fvc::ddt(rho, U)
              - fvm::laplacian(muEff, U)
              - fvc::div(tauMC)

[reza_65]

Originally Posted by buaawangwei

Hi alberto,
I want to know that rhoCentralFoam is a steady solver or a transient solver?Thank you

I am wondering how you could ask this question? This is can be ask by a first year undergrad student! You can check it easily in the solver description!

[reza_65]

Originally Posted by immortality

Hi
what does the lines for momentum solving in this solver mean?

// --- Solve momentum
        solve(fvm::ddt(rhoU) + fvc::div(phiUp));

        U.dimensionedInternalField() =
            rhoU.dimensionedInternalField()
           /rho.dimensionedInternalField();
        U.correctBoundaryConditions();
        rhoU.boundaryField() = rho.boundaryField()*U.boundaryField();

        volScalarField rhoBydt(rho/runTime.deltaT());

        if (!inviscid)
        {
            solve
            (
                fvm::ddt(rho, U) - fvc::ddt(rho, U)
              - fvm::laplacian(muEff, U)
              - fvc::div(tauMC)
            );
            rhoU = rho*U;
        }

whats the mathematical(CFD)form of the equation:

fvm::ddt(rho, U) - fvc::ddt(rho, U)
              - fvm::laplacian(muEff, U)
              - fvc::div(tauMC)

Hi,

I recommend you take a look at the paper by Christopher J Greenshields, Henry G Weller
You can find the paper in the following:

http://acemap.sjtu.edu.cn/paper/pape...perID=7FEEC30A