output angular velocity in post processing

Please login with a confirmed email address before reporting spam

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


4 Replies Last Post 25.06.2025, 17:33 MESZ
Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 1 month ago 26.05.2025, 10:19 MESZ
Updated: 1 month ago 26.05.2025, 10:36 MESZ

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
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)

Please login with a confirmed email address before reporting spam

Posted: 4 days ago 22.06.2025, 06:52 MESZ

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.

Henrik Sönnerlind COMSOL Employee

Please login with a confirmed email address before reporting spam

Posted: 13 hours ago 25.06.2025, 11:47 MESZ

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
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.

Please login with a confirmed email address before reporting spam

Posted: 7 hours ago 25.06.2025, 17:33 MESZ

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?

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?

Reply

Please read the discussion forum rules before posting.

Please log in to post a reply.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.