output angular velocity in post processing

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When simulating a round object that is rotating or rolling, how to output the angular velocity in post processing?


2 Replies Last Post 22 juin 2025, 06:52 UTC+2
Henrik Sönnerlind COMSOL Employee

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Posted: 4 weeks ago 26 mai 2025, 10:19 UTC+2
Updated: 4 weeks ago 26 mai 2025, 10:36 UTC+2

If it is a rigid object, it does have such variables defined. If not, the angular velocity is not necessarily uniform.

In the latter case, you could make use of the Average Rotation feature to determine an approximate rotation angle. In most cases, there is then a built-in variable like

solid.avgr1.th_tZ

for the angular velocity.

For cases when it is not present, you can compute the time derivative of the rotation using an expression like

d(solid.avgr1.thZ, TIME)

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Henrik Sönnerlind
COMSOL
If it is a rigid object, it does have such variables defined. If not, the angular velocity is not necessarily uniform. In the latter case, you could make use of the *Average Rotation* feature to determine an approximate rotation angle. In most cases, there is then a built-in variable like solid.avgr1.th_tZ for the angular velocity. For cases when it is not present, you can compute the time derivative of the rotation using an expression like d(solid.avgr1.thZ, TIME)

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Posted: 14 hours ago 22 juin 2025, 06:52 UTC+2

Dear Dr Sönnerlind Thank you very much for your answer. This is very helpful. I wonder where solid.avgr1.th_tZ can be found in equation view or output quantities in postprocessing? It might be number of dimensions dependent, because it is undefined in a 2d model.

Dear Dr Sönnerlind Thank you very much for your answer. This is very helpful. I wonder where solid.avgr1.th_tZ can be found in equation view or output quantities in postprocessing? It might be number of dimensions dependent, because it is undefined in a 2d model.

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