Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Electric field not adjusting with moving mesh
Posted 2013年3月27日 GMT-4 03:26 Low-Frequency Electromagnetics, Mesh, Structural Mechanics Version 4.3a 6 Replies
Please login with a confirmed email address before reporting spam
I have created a model which is effectively a capacitor with a moving plate. I have ground electrodes on the fixed top plate and +/-100V electrodes on the bottom moving plate. I am using ALE with an oscillating displacement to move the plate.
For stationary analysis when the electrodes are overlapping I can see a very strong electric field and when they are totally not overlapping, the E field is quite a bit weaker. This should all be accurate but when I do a time dependent analysis to move the bottom plate, the electric fields are not changing whether the electrodes are overlapping or not.
Please see the attached images. "0 off" is when there is total overlap, "15 off" is when there is no overlap, and "moving 15 off" is when the bottom plate starts off with no overlap and oscillates back and forth.
What am I missing in my model in order for the electric field to continually adapt to the top plate?
Thanks,
Jeff
Please login with a confirmed email address before reporting spam
If you use ES+ALE, you should use 2 parts for correct movement. Else your mesh will be strong deformed due to large motion.
I have modified your model (geometry with identity pair in the middle of air gap).
Ralf
Attachments:
Please login with a confirmed email address before reporting spam
Jeff
Please login with a confirmed email address before reporting spam
I have tried to incorporate solid mechanics with the previous model in order to apply a body load. Then I used the displacement (u) from solid mechanics as the mesh displacement for ALE but am I getting an error as shown in the attached figure. I tried applying the mesh displacement to only the device (not the air) and there were no errors but the electric fields weren't changing again like in the original model. So I believe the problem is that only part of the mesh (the device) has a displacement (u in air is zero).
So is there anyway I can express the displacement of the whole mesh as the displacement (u) of just the device? Or is this a totally different issue?
Thanks again,
Jeffrey
Attachments:
Please login with a confirmed email address before reporting spam
What should be the result of your simulation? If you want to see the mech. stress of your lower part, you can add a second study only with solid mechanics and use the same predefined displacement as in the first model.
In other case you can use your own differential equation (ge) like F=m*a for the movement.
Ralf
Please login with a confirmed email address before reporting spam
I have changed my design a lot but it's still relatively similar. But I am not trying to look for the mechanical stress.
So I have mass oscillating between two springs due to an applied body load. But I am also looking to figure out the electric field between the mass and some electric potentials nearby. So I followed your technique before by adding separate air mesh zones.
The problem is when I am trying to set the prescribed deformation of the moving mesh using the displacement output from solid mechanics. I want to set the prescribed deformation to v, but the mesh of air does not move in solid mechanics, so how can I specify the moving mesh as an output of solid mechanics?
Thanks,
Jeffrey
Edit: Nevermind I figured it out!
Please login with a confirmed email address before reporting spam