[mugabe2204]

Dear all,

I am doing simulations of 2D incompressible turbulent flow over NACA 2412 airfoil as part of my Master Thesis. I am absolutely stuck at a point to find separation point to introduce some active flow control. I can see the separation from velocity magnitude in paraview(image attached for angle of attack 11). But when I plot XY graphs in pressure and wall shear stress in paraview it gives a weird pattern and hides the point. The specific case was run in 8 cores.

Reynolds number : 3.1 *10 ^6
Turbulence Model : kkLOmega with turbulent intensity(I) 0.06 and viscosity ratio (vt)0.01 for calculating kt {1.5(I*u)^2} and omega {k/nu *vt }
Wall functions are not used.
Max yPlus initial and after final iteration are managed to be close to 1 with the mesh

Writing yPlus to field yPlus

Time = 20000
Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting turbulence model type RASModel
Selecting RAS turbulence model kkLOmega
bounding kt, min: 0 max: 305.053 average: 2.07085
bounding kl, min: 0 max: 467.602 average: 1.88121
bounding omega, min: 0 max: 47777.5 average: 280.85
kkLOmegaCoeffs
{
    A0              4.04;
    As              2.12;
    Av              6.75;
    Abp             0.6;
    Anat            200;
    Ats             200;
    CbpCrit         1.2;
    Cnc             0.1;
    CnatCrit        1250;
    Cint            0.75;
    CtsCrit         1000;
    CrNat           0.02;
    C11             3.4e-06;
    C12             1e-10;
    CR              0.12;
    CalphaTheta     0.035;
    Css             1.5;
    CtauL           4360;
    Cw1             0.44;
    Cw2             0.92;
    Cw3             0.3;
    CwR             1.5;
    Clambda         2.495;
    CmuStd          0.09;
    Prtheta         0.85;
    Sigmak          1;
    Sigmaw          1.17;
}

Patch 0 named WALL_UP
 d  : min: 1.25271e-06 max: 1.54599e-06 average: 1.35678e-06
 y+ : min: 0.00778992 max: 0.814644 average: 0.0946178

Patch 1 named WALL_DOWN
 d  : min: 1.11943e-06 max: 1.57132e-06 average: 1.319e-06
 y+ : min: 0.00333455 max: 1.14329 average: 0.105871

Writing yPlus to field yPlus

End

Please find the initial and final residual plots, pressure and wall shear stress plots here.

I have attached the 0, system, properties in constant folder, mesh images in the following attachements.

Some Information:
I have tried first order, second order schemes for gradient, divergence and laplacian with converging residuals. I varied parameters in fvSOlution like residual control, relative tolerance and other solvers parameters. I played around with boundary conditions from zerogradient, fixed values, freestream for pressure and velocity. I did mesh dependency checks by changing max yPlus till 0.1. Time Step continuity errors are close to 10 ^-11. I can immediately provide most of such results if any of you would like to have some other perspectives. And this is a blunt airfoil. the cd and cl are properly converging for most of these changes and I can provide any of that data.

My questions:
1. Is it something related to some post processing issues of reconstuct par near the wall ? Because the pattern of the jumps is once every 8 or 16 points(case is decomposed in 8 cores). I can provide csv format data or close up graph if you think it is.
2. Is it related to the initial pressure residual being high close to 10 ^-3 ? or Can I rely on the better converged final residuals ?
3. Any of the mesh issues ?
4. Can you suggest any other way to find separation point ?
5.Kindly suggest any of your ideas and I can try it out in the cluster and get back.

Any help on this issue is deeply appreciated as I am stuck with from many days. Kindly let me know for any further details

Regards,
Bhanu

[mugabe2204]

Kindly forgive me and let me know if I made some errors in posting the thread and I can update with the same for next threads. Please find the other files here.

[mugabe2204]

Mesh files