SimScale CAE Forum

Failed CFD Simulation of a Car

Im trying to perform an incompressible fluid simulation to a car but it keeps diverging.Im getting a really large drag coefficient and Im not really sure why.I already try to refine the mesh around the car but it still didnt work.What should I do to solve this?I think Im missing something but I really cant identify what it is.This is the link of my project
Numerical Investigation | SimScale
Thanks in advance for the advice

Hey, @rian_garcia

There a couple things that could help.

  1. Your mesh sizing is quite small, you could easily increase fineness on your geometry body itself (surface refinement) not just a region. at least 6-800k cells is a good size based on your geometry complexity to add more measurement points.

  2. Your floor should be set to a moving wall at the same velocity as your inlet speed (-30)

  3. the bounding box cell sizes need to be squares. you can see in the x direction the cells are too long, making rectangles.

  4. To get any kind of accuracy you need to add a boundary layer refinement. currently you have none applied. This means you need to determine the correct Y+ value for your simulation.

Based on your current simulation, i would suggest reading more about this whole process. Simscale has some great articles that you can find in the documentation and forum. There are many factors needed to create a successful and reliable simulation. If you dont have a good foundation then you will just waste your core hours and time, while becoming even more frustrated.

Here are the best places to learn. There are also many step by step tutorials on many different simulation types

Good luck,


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