# Mirror a mesh

Hello!

I am from a Formula SAE team. After finishing our stantard simulations we decided to carry out a cross-wind simulation. We were thinking of simulating this by properly imposing speed on the bounding box.

The problem is that we can no longer use the central symmetry plane in the simulation.
However, the mesh is still symmetrical. So we thought we could mesh half the car and then mirror the mesh.
Is it possible to mirror a mesh in SimScale? How do you do that?

Thanks in advance
Lorenzo

Hi Lorenzo,

I believe you can do this by first meshing the car geometry with the bounding box “cutting” the car in half and then setting the boundary condition where the car is being cut in half to a symmetry condition.

To impose a cross-wind factor you will have to split the velocity components into two components since the bounding box is a rectangle of sorts. The opposite ends to the inlet condition will then need to be an outlet.

This project and this project should give you a good idea of how to do so.

Cheers.

Regards,
Barry

Ok, let me understand. The symmetry condition on the “half car bounding box” has an influence only on the mesh geometry? I’m asking: using that condition, will Simscale perform the simulation on the whole car?

I always thought that the symmetry condition concerned both the mesh geometry and the simulation process.

I want the simulation to be performed on the whole car because, obviously, point A is swept by a clean flow while point B will be swept by a turbulent flow. Accordingly, the symmetry isn’t valid anymore when I perform a simulation. Am I wrong?

Thank you again
Lorenzo

Hi Lorenzo,

as you already said point B will feel another flow than point A thus using the usual symmetry plane in the middle won’t make much sense here. I would just use the whole car and make sure the domain is big enough splitting your velocity components in x & y and start a study as usual. Feel free to reach out to Barry (@Get_Barried) and me if you need something.

Best,

Jousef

Hi Lorenzo,

Sorry for the delay in reply, was a little caught up.

Yes what Jousef mentioned here is correct, it will not be possible then if you want to capture effects on the other side of the car as well. The symmetry bounding condition will not “dual simulate” the geometry. Hence you will need to simulate the entire geometry in order to observe effects of a non symmetrical inlet direction on the other half of the car.

Cheers.

Regards,
Barry