Problem with flow speed

Project Support
1

Hello,
I am running a simulation with two vehicles in a platoon sequence at a flow speed of 60 m/s. When I check the post process results, the forces and moments coefficients plots go crazy for the leading vehicle and I also find out that there is a region in the geometry model that reaches 5000 m/s…

Captura de pantalla (24)
Captura de pantalla (24)1563×761 111 KB

I have already tried simulating those exact same vehicles but with a slightly larger separation distance between them and the results seemed fine, I just do not understand why for this case the flow goes crazy at the bottom of the leading vehicle.
Here is the link to my project, the simulation that I am experiencing problems with is called “Ahmed body-GTS-0.25L”: Ahmed body 2 by pl00447 | SimScale

Thank you for your help

2

Hello pl00447

please have a look at this article about diverging simulations.

Another tip I could give you is to try the hex dominant mesher, which can create better results for more mesh-aligned flow.

You can also try to reduce the relaxation factor for velocity, this should also result in a more stable simulation.

Best regards Sebastian