# Rotating Mesh around Local Axis

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 November 9, 2012, 17:35 Rotating Mesh around Local Axis #1 New Member   Join Date: Nov 2012 Location: Scotland, UK Posts: 19 Rep Power: 13 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.

 November 13, 2012, 03:29 #2 New Member   Join Date: Nov 2012 Location: Scotland, UK Posts: 19 Rep Power: 13 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?

 November 21, 2012, 03:07 #3 New Member   Join Date: Nov 2012 Location: Scotland, UK Posts: 19 Rep Power: 13 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.

 October 14, 2021, 16:01 #4 New Member   Nasos_bal Join Date: Oct 2021 Posts: 8 Rep Power: 4 Hello! I have a similar problem. Did you find the solution?

July 9, 2023, 07:56
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Quote:
 Originally Posted by Nasos_bal 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?

 July 9, 2023, 11:17 #6 Senior Member   Yann Join Date: Apr 2012 Location: France Posts: 1,142 Rep Power: 27 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

 July 9, 2023, 13:51 #7 Member   Join Date: Apr 2022 Posts: 31 Rep Power: 4 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

 July 10, 2023, 03:35 #8 Senior Member   Yann Join Date: Apr 2012 Location: France Posts: 1,142 Rep Power: 27 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 AMR96 likes this.

 July 12, 2023, 04:51 #9 Member   Join Date: Apr 2022 Posts: 31 Rep Power: 4 Thank you very much for your help Yann! Best, Amirmohammad Yann likes this.

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