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Dual-Element Front Wing Case Using SST K-OMEGA TURBULENCE MODEL

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Old   January 14, 2019, 07:13
Default Dual-Element Front Wing Case Using SST K-OMEGA TURBULENCE MODEL
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Jesús Miguel Sánchez
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Hello everyone!!

I have tried to run this case in ground effect. The case doesn't seem to converge and the residuals go no lower than 10^-3. I use the turbulence model SST k-omega with SIMPLE

I will explain the case below:


To simulate the case of a FSAE dual-element front wing in ground effect. For that, the patches of the grid are:

Wing = Wall

Road = Wall

Top = Patch

Inlet = Patch

Outlet = Patch

The boundary conditions I use are:

For U:

Wing = noSlip

Road = movingWallVelocity

Top = inletOutlet

Inlet = inletOutlet

Outlet = inletOutlet

For p:

outletInlet for the patches with inletOutlet

the boundary conditions for the wall patches are set as zeroGradient.

For k and omega:

I use the same boundary conditons as for the U on the patches.

For the wall patches, I use fixedValue 1e-10 on the k file and omegaWallfunction (freestream value calculated from the formula) on the omega file.

For the nut:

all calculated, except for the wall pacthes that have fixedValue 0.

This means that I am trying to solve the Boundary Layer, as that is the main functionality for this turbulence model.

The problem is, as said before, that I cannot obtain good residuals with a converged solution.

I have tried different y+ values from 5 to 1 (and even lower), but it doesn't work.

Any idea of what the problem could be?

The Reynolds number for this case is of 524000, therefore, it believe that this case shifts more towards Low-Re case than High-Re. I would like to receive some suggestion, because I have tried several things, such as using wall functions and other settings and I do not get the desired results.
Thank you for your time.

Best Regards

PS: The grid values are:

Aspect ratio: Along the wing = around 4
Skweness equiangle = around 0.6 as max, the average is 0.22
Aspect ratio = the average is around 5 but I have a maximum value of 750 due to the structured mesh for the boundary layer of the road. This cell is located very far away from the FW upstream (Near to the inlet).

I use a hybrid mesh consisting of structured mesh on the road and on the wing elements and unstructured mesh along the whole rest of the grid (Advanced Front Ortho). I use also Pointwise to do this.
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Old   December 14, 2020, 13:48
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Gabriel Benitez
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Hey Jesus!

Did you manage to solve the problem?
In my case I am studying the flow through a 2D section of a rear wing formed by two profiles. I have used AFO and T-Rex algorithm to create the mesh and I am using K-omegaSST.
It happens to me like you, the simulations do not converge and I do not know what it can be.
I wonder if it is due to k-omegaSST, or if it is from OpenFOAM or mesh case settings.
I would appreciate your help
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simple algorithm, sst k-omega, sst k-w, sst komega, yplusras

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