[karchouille]

Hello everyone,

I am currently designing a front wing that I want to optimize through CFD. I have done research about my problem before posting.

Here are the parameters of my simulation :
- Steady state
- Constant density (air at 25°C)
- Segregated flow
- SST K-Omega turbulence
- All y+ wall treatment (all wall Y+ values on the wing are below 1)
- 6.5 million polyhedral cells with many surface & volumetric controls around the body and in the wake zone.

The things I have noticed about this simulation are the high amount of residuals even with some mesh refinement cycles and the non-convergence of the physical values I want to measure.

First, I have created a threshold for each residual (X Y Z Momentum, Specific Dissipation Rate and Turbulent Kinetic Energy) to show them on a geometry scene. I used the "Query" command to have the min and max value of each residual and took the 20% extreme values to define the thresholds.
Then I created a volumetric control around the concerned cells and set the cell size to a smaller value.

I have repeated this cycle 5 times and found out that the RMS values showed on the Residuals plots decreased a little bit at each refinement cycle, reaching a non-normalized value of about 1E-04 (except for the Sdr). However the auto normalized values are about 1E-01.
I think that there is not much more to do according to the enclosed screenshot named "Residuals visualizing". The Momentum residuals are in the far wake but the top 20% of the TKE are still just behind the body.

The physical values I want to measure (Drag and Lift) do not seem converged as they oscillate randomly. I have plotted pressure contour around the body and it seems rather logical.

I have checked the mesh with a complete diagnostic and used thresholds to show Skewness angle (>85°), Cell quality (<1E-05) and Volume change (<1E-02) but no cell is concerned and the mesh is topologically valid.

I do not think I can consider this simulation converged. What else do you think I could do to make it converge ?

Thank you in advance.
Please find some screenshots below.