[praveen]

I am having some problem with a NACA0012 test case using rhoCentralFoam. The freestream mach is 0.75 and there is a shock. I have attached some pictures. There is something wrong with the bcs.

Some of the input options are listed below. Other input files are same as here

http://gfoam.svn.sourceforge.net/vie...12_7k_M075_a2/

Hope somebody can point out the mistakes.

0/p

internalField   uniform 85418.9;

boundaryField
{
    inlet-outlet
    {
        type            fixedValue;
        value           uniform 85418.9;
    }

    body            
    {
        //type            slip;
        type            zeroGradient;
    }

    defaultFaces    
    {
        type            empty;
    }
}

0/T

internalField   uniform 260;

boundaryField
{
    inlet-outlet
    {
        type            fixedValue;
        value           uniform 260;
    }

    body            
    {
        //type            slip;
        type            zeroGradient;
    }

    defaultFaces    
    {
        type            empty;
    }
}

0/U

internalField   uniform (242.284 8.46075 0);

boundaryField
{
    inlet-outlet
    {
        type            fixedValue;
        value           uniform (242.284 8.46075 0);
    }

    body            
    {
        type            slip;
    }

    defaultFaces    
    {
        type            empty;
    }
}

constant/thermophysicalProperties

thermoType      ePsiThermo<pureMixture<constTransport<specieThermo<eConstThermo<perfectGas>>>>>;

mixture         air 1 28.965 717.625 0 0 0.72;

[taxalian]

hi praveen,
Is the solution converges well and where can i really see that you used the rhoCentralFoam for your problem.

[praveen]

Everything in the above link remains same for rhoCentralFoam except you have to change to

fluxScheme Kurganov; // or Tadmor

in system/fvSchemes. The files can be downloaded here

http://gfoam.svn.sourceforge.net/vie...5_a2/?view=tar

[naveen]

hi praveen,

I am also trying for different airfoil simulation using rhoCentralFoam using different boundary condition at mach no=0.7. even i am also getting same error wat u r getting on airfoil surface for unstructured grid. But when i solved for structured grid (same airfoil wat i used for unstructured) i am getting perfect solution using rhoCentralFoam for C Grid without any disturbances on airfoil surface. Could you please tell me what s da solution for this type of problem, if u have solved.....

----Regards---------

NAVEEN.K.M
NAL
BANGALORE

[praveen]

I dont know whats the problem. I too got proper result with structured grid for naca case.

[naveen]

OK....letś try some other way....can u give me your mail id....

NAVEEN.K.M

[naveen]

hi praveen,

I got the proper results for airfoil using rhoCentralFoam for unstructured grid same as structured grid.

Regards

NAVEEN

[Solarberiden]

Hi guys, I encountered the same problem, could you please tell me how do you solve the problems on unstructured grid? Thanks a lot!~

[praveen]

See http://www.cfd-online.com/Forums/ope...tml#post317918

[venkataramana]

can anybody provide details about preconditioning for the above solver for Mach number approaching zero.

thanks in advance,

Regards.

[Solarberiden]

Originally Posted by venkataramana

can anybody provide details about preconditioning for the above solver for Mach number approaching zero.

thanks in advance,

Regards.

The above solver is naturaly a density based solver, so for the low Re number or Mach number problems, the problem won't be appropriate as far as I know, you could have a go with the pressure based solver like the prevails philosyphy which is used by most of the OpenFOAM solvers, PISO or SIMPLE family solvers.
regrads.
TCH

[venkataramana]

solvers for compressible flows always has Mach number is greater than that of incompressible flows, using preconditioning we can use compressible flow solvers for solving incompressible N-S equations ( having Mach Number nearer to zero)
can anybody provide details about the code to implement in openFoam.

here I am attaching the link which contains the details about the method.

http://openfoamwiki.net/index.php/TestLucaG.


thanks in advance
regards.

[dancfd]

Hello all,

I am trying to simulate a NACA 0012 airfoil in transonic flow. I believe that rhoCentralFoam would be the best solver for the compressible & transient simulations. However, I have not used a density-based solver before and I am struggling with a few issues:

1. What is the best way to check for convergence? When using simpleFoam, I plotted Ux_0 and p_0 residuals. In rhoCentralFoam, there is no p_0 residual (obviously) and the rho_0 residual is 0 from start to finish.

2. Here is what a typical timestep looks like in the log. I find it strange that all of the rho equations have 0 residual and 0 iterations. Any advice?

Mean and max Courant Numbers = 0.00853124 0.92921
deltaT = 4.19687e-07
Time = 8.52996e-07

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
diagonal:  Solving for rhoUx, Initial residual = 0, Final residual = 0, No Iterations 0
diagonal:  Solving for rhoUy, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for Ux, Initial residual = 3.21903e-06, Final residual = 2.88895e-09, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 2.167e-06, Final residual = 5.51926e-09, No Iterations 2
diagonal:  Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for e, Initial residual = 5.09557e-06, Final residual = 1.47595e-08, No Iterations 2
smoothSolver:  Solving for omega, Initial residual = 3.91917e-06, Final residual = 3.3493e-10, No Iterations 2
bounding omega, min: -6231.35 max: 239456 average: 1107.8
smoothSolver:  Solving for k, Initial residual = 0.00250408, Final residual = 1.13916e-08, No Iterations 2
ExecutionTime = 0.28 s  ClockTime = 0 s

3. My simulation produced results that compared well to experiment in simpleFoam, however the Cp plot is a mess in rhoCentralFoam (both plots attached). Any ideas?

Thank you for any suggestions,

Dan

[Farshad_Noravesh]

Hi,

Is there anybody who can help us with this question because many good people have asked it and no one has ever replied properly.

Kind Regards,

Farshad

[praveen]

Have you seen this post

http://www.cfd-online.com/Forums/ope...ible-code.html

[Farshad_Noravesh]

Hi,

I read that and he mentioned that: "The obliqueshock and forwardstep cases run fine but there is some problem with the naca case. The case runs but the solution has strange behaviour near airfoil surface "

So i think the airfoil is a problem but why? The other problem is that the kurganov-tadmor or any other flux scheme is not available.

Kind Regards,

Farshad

[JohanAdam]

Hi,

Using Vuorinen's slides on "Compressible Runge-Kutta 4 LES-Solver to OpenFOAM", I implemented RK in rhoCentralFoam.

This seems to provide a notable improvement in removing those numerical instabilities. I am still using vanLeer in fvScheme and not gamma.

Regards
Johan

[mkhm]

Hi Daniel,

Did you find any answer to your question about convergence criteria for rhoCentralFoam ?