High Velocity in an incompressible analysis of a FSAE wing

Using SimScale Fluid Flow / CFD
1

Hello There,

I am trying to simulate a FSAE Wing but even though the mesh seems perfect I am having some problemas in the post-results. The Velocity seems to go beyond 200 m/s even though the initial velocity is 15m/s. The air flow starts to acelerate ritgh in the beginning of the winf tunnel.

The link of the project is below.

Thank You for your help

image

1 Like
2

Hi this is Fillia :slight_smile:

The issue here seems to be mesh related - the rest of the settings are alright-.

These are my suggestions:

  1. Use this vehicle tutorial as reference: Aerodynamic Flow Behavior Around a Vehicle Tutorial | SimScale

  2. Reduce the Enclosure’s size - as in Figure 5 -, or even better, simulate half the model with Symmetry.

  3. Switch to the Standard mesher and use refinements like in the vehicle tutorial. ( 2 region refinements and a local element size, the boundary layer is generated automatically).

  4. Even if the layers are generated automatically, you can control their characteristics on the main mesh tab. Use this calculator: https://www.pointwise.com/yplus/index.html

You can always check the mesh quality using this guide:

Let me know what you think.

Best regards,
Fillia

3

Thank you for the quick reply. I will try to generate this mesh but I can’t quite understand why my mesh is not working. The Y+ seems whithin range which means the problem is not the mesh near the wing but the mesh in the Bounding Box as Well.

4

I tried a new mesh with the simmetry condittion and the mesh seems to have a good quality, but i keep having the same problem with the velocity and pressure. The pressure around the wing does not match the velocity with the bernoullis laws. I don’t quite understand why the problem might be in the mesh if the boundary layer seems ok and the mesh quality test indicates no problem.

The project is below.

5

I believe the problem is with the difference between the mesh refinement within the cartesian boxes. I have a cartesian box with a refinement level of 7 and the outer one has one of 2. As you can see in the picture below, the problem of the velocity seems to originate right in the intersection of both.

I appreciate the help!

image
image1070Ă—843 78.8 KB

1 Like
6

Hi there, I hope you had a lovely weekend!
Indeed, if there is a big difference between refinement levels, this could cause issues. Did you try a smoother transition between region refinements?

Best regards,
Fillia