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-   -   LaunderSharmaKE (https://www.cfd-online.com/Forums/openfoam-solving/119121-laundersharmake.html)

immortality June 10, 2013 09:44

LaunderSharmaKE
 
Hi
when I wanted to use LaunderSharmaKE as a low-Re turbulence model,it complained to add these terms:
Code:

grad(U.component(0)) Gauss linearUpwind;
    grad(grad(U.component(0))) Gauss linearUpwind;
    grad(U.component(1)) Gauss linearUpwind;
    grad(grad(U.component(1))) Gauss linearUpwind;
    grad(U.component(2)) Gauss linearUpwind;
    grad(grad(U.component(2))) Gauss linearUpwind;
    grad(sqrt(k)) Gauss linear;

linear method gave very high U residuals and when I set it to linearUpwind this error occurred:

Code:

Creating turbulence model

Selecting turbulence model type RASModel
Selecting RAS turbulence model LaunderSharmaKE
LaunderSharmaKECoeffs
{
Cmu            0.09;
C1              1.44;
C2              1.92;
C3              -0.33;
sigmak          1;
sigmaEps        1.3;
Prt            1;
}

fluxScheme: Kurganov

Starting time loop

Mean and max Courant Numbers = 59.43127 2063.351031
deltaT = 2.423067604e-10
Time = 2.42307e-10

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
[0] swak4Foam: Allocating new repository for sampledGlobalVariables
[1] swak4Foam: Allocating new repository for sampledGlobalVariables
[2] swak4Foam: Allocating new repository for sampledGlobalVariables
[3] swak4Foam: Allocating new repository for sampledGlobalVariables
smoothSolver:  Solving for Ux, Initial residual = 1, Final residual = 5.242179386e-10, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 4.815464786e-13, No Iterations 2
diagonal:  Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for h, Initial residual = 6.065092588e-05, Final residual = 1.607770036e-09, No Iterations 1
time step continuity errors : sum local = 0, global = 0, cumulative = 0
[1] [2]
[2]
[2] --> FOAM FATAL IO ERROR:
[2] attempt to read beyond EOF
[2]
[2] file: IOstream.gradSchemes.grad(U.component(0)) at line 0.
[2]
[2]    From function ITstream::read(token&)
[2]    in file [0] db/IOstreams/Tstreams/ITstream.C at line 83.
[2]
FOAM parallel run exiting
[2]

[0]
[0] --> FOAM FATAL IO ERROR:
[0] attempt to read beyond EOF
[0]
[0] file: /home/ehsan/Desktop/Central/Turbulent_WR/low-Re/turbulent_lR700*50/processor0/../system/fvSchemes.gradSchemes.grad(U.component(0)) at line 51.
[0]
[0]    From function ITstream::read(token&)
[0]    in file db/IOstreams/Tstreams/ITstream.C at line 83.


eysteinn June 10, 2013 10:22

Hi,

If you go to the tutorial folder and write
grep -r linearUpwind .
Then you see that you need an extra term, grad(U)

( Also you probably ment to modify the convection terms in the div() subdict and you don't need to modify each component separately )

(I also noticed that you are running unsteady and your timestep is 1e-10.
I'm not sure what kind of a simulation you are running but if you intend to simulate
1 second of flow it will take very very long time.)

Edit: ok so you are probably using some variable step size I guees, that could explane the time step size :)

immortality June 10, 2013 11:22

Hi Eystein
how can I modify the div() term?
I use maxCo and when I increase it to 2 it crashes but time step is still too low.
my case is compressible unsteady and use rhoCentralFoam.

eysteinn June 11, 2013 02:40

Hi,

It is done in the divScheme sub-dictionary.

Take a look here and in the tutorials folder you can see some examples
OpenFOAM-2.2.x/tutorials/compressible/

/Eysteinn


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