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Dual-Element Front Wing Case Using SST K-OMEGA

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Old   January 14, 2019, 09:24
Default Dual-Element Front Wing Case Using SST K-OMEGA
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Jesús Miguel
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Hello everyone,

I am writting my final thesis on a Dual-Element Front Wing in Ground Effect case.

For that, I use SST K-OMEGA with SIMPLE algorithm.

The FW (Front Wing) travels at a speed of 13.89 m/s (50 km/h approx.), which gives me a Re number of 524000.

The problem is the following. I am trying to solve the boundary layer without the use of wall functions and I don't seem to get any converged results. The residuals do not go any lower than 10^-3 .

I have refined several times my mesh untill getting to an average of y+ 1.5- 1.0 approx.

I have tried almost everything I have in mind. I do not know if something escapes out of my knowledge scope.

To get a better view of the case, I wil describe the grid and the settings.

Grid:

I use a hybrid mesh that consists of a structural mesh on the wall of the elements of the FW and along the road and of an unstructured mesh around the rest of the domain (Advanced Front Ortho). For the meshing, I use Pointwise.

The quality check values I obtained are the following:

  • Area Ratio = 1 .19 (average) 5.37 (max)
  • Aspect Ratio = 5.15 (average) 750 (max) -> this value corresponds to a cell upstream very far away from the FW.
  • Skweness Equiangle 0.11 (average) 0.60 (max)

Patches:

  • Patch: top, inlet, outlet
  • Wall: wing, road

Set-up:

U:

  • inletOutlet for the patches
  • noSlip for the wing patch
  • movingWallVelocity for the road patch


p:

  • outletInlet for patches
  • zeroGradient for wall patches



k & omega:

  • same BC's as U for the patches with calculated freestream values
  • omegaWallFunction for the wall patches with freestream value
  • fixedValue 1e-10 for k on the wall patches.



nut:

  • calculated for patches
  • fixedValue 0 for wall patches


I do not know if the problem is that I should use a wall function or a low Re wall function.

Should I refine below y+ 1?

Hope you could help me.

Thank you for your time.

Best Regards,

Jesús Miguel
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openfoam, sst k-omega, sst komega, yplus

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