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output angular velocity in post processing
Posted 25 mag 2025, 05:11 GMT-4 Results & Visualization, Structural Mechanics 4 Replies
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When simulating a round object that is rotating or rolling, how to output the angular velocity in post processing?
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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)
-------------------Henrik Sönnerlind
COMSOL
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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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If you have added an Average Rotation node, you will find the results under Solid Mechanics -> Displacement -> Average rotation. This is independent of space dimension.
If you, in general, want to search for a variable, use Ctrl-F.
-------------------Henrik Sönnerlind
COMSOL
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Dr Sönnerlind Many thanks. Now I can see solid.avgr1.thZ after adding an Average Rotation node. However it returns 0. I need some tutorials on 'Average Rotation node', if there's any?