Brian Bueno
Ansys Employee

Josef Mrtka

This looks like a problem that might be resolved by increasing the fidelity of the analysis.  However, as you’ve noticed, there are some limitations on the level of detail that can be obtained in a large model with relatively small/thin parts.

My recommendation would be to examine the rear spoiler on its own.  You can hide the rest of the car and create a new solution with a smaller fluid volume.

I actually hosted a webinar where I used a very similar example in a fluid analysis: 

Webinar Recordings: Discovery Live Tips & Tricks

This article provides further explanation of fidelity and the accuracy of simulations in Discovery Live: 

Discovery Verification and Benchmark Cases