Rotating Mesh around Local Axis
 

Hi,

I'm running some external aerodynamic CFD studies on a Formula Student car as part of my thesis, and I want to simulate wheel movement. However, since the wheels are not perpendicular to the ground, they have some camber and toe angles, I cannot rotate them around the y axis, so how would I go about defining an axis aligned with the wheel orientation. I do not know how hard this would be to implement as I am just starting out using OpenFOAM.

regards.

so I did some digging and found the rotateMesh command, and if I read the documentation correctly, I would split my mesh into 5 parts - 4 wheels and the body. Then use rotateMesh (initial orientation where 1 = 90deg?) (final orienation) -time :1000

which should rotate the wheel till t=1000?

figured it out, you split the mesh into 5 parts, wheels and body. Then use a rotatingWallVelocity boundary conditions for them. However, the axis is labelled as

axis (0 0 1);

Which would rotate about the z axis, if I used (0.5 0.5 0); instead (or is this just a simple 1 is on, 0 is off), would that rotate the mesh 45 degrees to the x and y axis then?

If so, and I wanted to say turn the wheels 25 degrees and run them, I'd have it (0.278 0.722 0), although probably best picking something that divides into 90 better.

Hello! I have a similar problem. Did you find the solution?

Hi,

Did you find a solution for this?

Does this boundary condition work for a wheel that has toe-in and camber angles?

Hello AMR96,

The rotatingWallVelocity takes 3 parameters: angular velocity, origin and axis of rotation. (https://doc.openfoam.com/2306/tools/...gWallVelocity/)

So as long as you properly define these parameters for each wheel, you are good to go.

Cheers,
Yann

Hi Yann,

Thanks for your reply and the link. Just to be sure I understood everything, I'll explain my situation and what I did.

The original axis of rotation of my wheel was (0,0,1). But I applied a camber angle which in my case was around the x axis and a toe-in angle around the y axis. Then I used the 3D rotation matrix around x and y and applied it to the initial vector (0, 0, 1). I used the result as the new axis of rotation.

Is this the correct way to generate an input for the axis vector?

Best,

Amirmohammad

Hello Amirmohammad,

It sounds right indeed. You can then check the wall velocities in ParaView to see if you get the expected result.

Another way to get the vector is to take 2 points along the wheel axis in your CAD software, and measure the (dx,dy,dz) between these 2 points. (useful when you get a CAD file with wheels already in position)

Cheers,
Yann

Thank you very much for your help Yann!

Best,

Amirmohammad