FSAE car mesh study external aerodynamics convergence problem

math_marques96 · September 11, 2019, 8:13pm

Hello

I am doing a mesh study for an external aerodynamics simulation of a FSAE car

I made 3 meshes with the only difference between them been the bounding box resolution.
There is one mesh with 5.2 millions cells(mesh 3), another one with 6.4 millions cells(mesh 4), and one with 7.5 millions cells(mesh 2).

I used the same simulation setup to run the simulations of this three meshes.
The mesh 3 simulation converged, but the mesh 2 and mesh 4 did not. Below there is a image of the force plots of these three simulations:

Mesh 3

Mesh 4

Mesh 2

The link of the profect is SimScale

I would greatly appreciate help with this.

Regards

@jousefm @anirudh2821998 @Get_Barried @pfernandez

Get_Barried · September 12, 2019, 5:48am

Hi @math_marques96,

Try disabling potentialfoam and re-running the sim.

Cheers.

Regards,
Barry

math_marques96 · September 13, 2019, 12:18am

I tried to run the “mesh 4” with the potentialfoam disabled, but unfortunately the simulation also diverged.

Get_Barried · September 13, 2019, 2:28am

Hi @math_marques96,

So far the boundary conditions and numerical schemes are correct. What is the difference between mesh 2, 3 and 4?

math_marques96 · September 13, 2019, 12:05pm

I only changed the bounding box resolution values between them, with the mesh 2 been the most refined, the mesh 4 the intermediate and the mesh 3 the less refined.

DaleKramer · September 13, 2019, 2:08pm

I am not too sure of your specific problem but I can suggest that you could have saved a bunch of core hours and have tested more parameter changes to fix this in a shorter real time if you were watching the ‘Force and moments’ plots during the runs that failed. I think that I would have stopped them all in the 150 to 250 second area since you can see the divergence starting that early on these plots.