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-   -   NACA0012 with rhoCentralFoam (http://www.cfd-online.com/Forums/openfoam/87870-naca0012-rhocentralfoam.html)

praveen May 1, 2011 09:33

NACA0012 with rhoCentralFoam
 
3 Attachment(s)
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
Code:

internalField  uniform 85418.9;

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

    body           
    {
        //type            slip;
        type            zeroGradient;
    }

    defaultFaces   
    {
        type            empty;
    }
}

0/T
Code:


internalField  uniform 260;

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

    body           
    {
        //type            slip;
        type            zeroGradient;
    }

    defaultFaces   
    {
        type            empty;
    }
}

0/U
Code:


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
Code:

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

mixture        air 1 28.965 717.625 0 0 0.72;


taxalian May 1, 2011 14:32

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

praveen May 1, 2011 22:13

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 June 3, 2011 05:07

NACA0012 with rhoCentralFoam
 
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 June 3, 2011 05:20

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

naveen June 3, 2011 05:27

NACA0012 with rhoCentralFoam
 
OK....letś try some other way....can u give me your mail id....

NAVEEN.K.M

naveen June 8, 2011 06:01

NACA0012 with rhoCentralFoam
 
hi praveen,

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

Regards

NAVEEN

Solarberiden July 28, 2011 12:00

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 July 28, 2011 12:42

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

venkataramana July 28, 2011 21:31

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

thanks in advance,

Regards.

Solarberiden July 29, 2011 00:36

for the mach number approaching to zero
 
Quote:

Originally Posted by venkataramana (Post 317962)
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 July 29, 2011 03:49

hi
 
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 December 7, 2011 23:49

2 Attachment(s)
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?

Code:

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 December 12, 2012 04:02

same question for zero density
 
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 December 12, 2012 04:16

Have you seen this post

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

Farshad_Noravesh December 12, 2012 04:33

how about kurganov-tadmor or AUSM+?
 
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 July 11, 2013 08:29

naca0012 rhoCentralFoam instabilities
 
1 Attachment(s)
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


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