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How to couple Electrostatics and Solid Mechanics in COMSOL 4
Posted Jun 19, 2010, 1:25 p.m. EDT 4 Replies
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Hi comsolers,
I'm a newbie in COMSOL. I'm trying to couple the force (named Fes) produced by a potential difference between a ground plane and a mechanical structure (I'm also using a moving mesh). I tried to use the "Edge load" boundary condition in the Solid Mechanics physic, using the variables "es.Tx_Fes" and "es.Ty_Fes" as the edge load. But the solver keeps saying "Failed to evaluate expression" (I think that COMSOL isn't finding the force variables)
Any suggestions?
By the way, how can I know the name of the variables produced by COMSOL? (like the es.Tx_Fes) And, do I have to define the order in which the different physics are going to be solved? I mean, if the Structural Mechanics depends on the Electrostatics, this last one has to be solved first?
PD: I've also tried to use the COMSOL 3.5 ale_cantilever_beam example but it doesn't seem to work in COMSOL 4.
I'm a newbie in COMSOL. I'm trying to couple the force (named Fes) produced by a potential difference between a ground plane and a mechanical structure (I'm also using a moving mesh). I tried to use the "Edge load" boundary condition in the Solid Mechanics physic, using the variables "es.Tx_Fes" and "es.Ty_Fes" as the edge load. But the solver keeps saying "Failed to evaluate expression" (I think that COMSOL isn't finding the force variables)
Any suggestions?
By the way, how can I know the name of the variables produced by COMSOL? (like the es.Tx_Fes) And, do I have to define the order in which the different physics are going to be solved? I mean, if the Structural Mechanics depends on the Electrostatics, this last one has to be solved first?
PD: I've also tried to use the COMSOL 3.5 ale_cantilever_beam example but it doesn't seem to work in COMSOL 4.
4 Replies Last Post Jun 25, 2010, 9:45 a.m. EDT
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Posted:
1 decade ago
Hi
a few suggestions:
1) all translatings of older 3.5 to 4 are not fully up working yet, but most of the stuff gets translated, and I find it very interesting because I have learn what corresponds to what in V4 (I'm not fully up but I'm progressing, also by learning how COMSOL translates the old files).
2) to see the equations and to get some info on the internal variables, turn on te equations in the preferences
3) As you said, the order is important when you couple physics. Trying to solve everything is often difficult, so its mostly better to decide how to segregate the physics and loop around in a thought-out way. As you sa I belive to, from the little I got from your model description, that you should solve for E or A first and then run the structural and loop around. This is one of the subtilities in multiphysics solving, and COMSOL proposes several ways to handle this. Several cases also discussed on the forum, use the searcch.
Have fun Comsoling
Ivar
a few suggestions:
1) all translatings of older 3.5 to 4 are not fully up working yet, but most of the stuff gets translated, and I find it very interesting because I have learn what corresponds to what in V4 (I'm not fully up but I'm progressing, also by learning how COMSOL translates the old files).
2) to see the equations and to get some info on the internal variables, turn on te equations in the preferences
3) As you said, the order is important when you couple physics. Trying to solve everything is often difficult, so its mostly better to decide how to segregate the physics and loop around in a thought-out way. As you sa I belive to, from the little I got from your model description, that you should solve for E or A first and then run the structural and loop around. This is one of the subtilities in multiphysics solving, and COMSOL proposes several ways to handle this. Several cases also discussed on the forum, use the searcch.
Have fun Comsoling
Ivar
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Posted:
1 decade ago
Many thanks for your answer Ivar, it has been very helpful.
A question jumped into my mind just after reading your answer. How can I choose the order of the simulation of the different physics? Do I have to do different studies and check which physic I am going to solve?
I have searched in the forum, but all the information is for v3.5 or lower. Do you know when COMSOL is going to upgrade its website with examples and tutorials?
Thanks for your time, I really appreciate it.
Jordi
A question jumped into my mind just after reading your answer. How can I choose the order of the simulation of the different physics? Do I have to do different studies and check which physic I am going to solve?
I have searched in the forum, but all the information is for v3.5 or lower. Do you know when COMSOL is going to upgrade its website with examples and tutorials?
Thanks for your time, I really appreciate it.
Jordi
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Posted:
1 decade ago
Many thanks for your answer Ivar, it has been very helpful.
A question jumped into my mind just after reading your answer. How can I choose the order of the simulation of the different physics? Do I have to do different studies and check which physic I am going to solve?
I have searched in the forum, but all the information is for v3.5 or lower. Do you know when COMSOL is going to upgrade its website with examples and tutorials?
Thanks for your time, I really appreciate it.
Jordi
A question jumped into my mind just after reading your answer. How can I choose the order of the simulation of the different physics? Do I have to do different studies and check which physic I am going to solve?
I have searched in the forum, but all the information is for v3.5 or lower. Do you know when COMSOL is going to upgrade its website with examples and tutorials?
Thanks for your time, I really appreciate it.
Jordi
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Posted:
1 decade ago
Hi
I have heard that COMSOL is working on it (I'm not Comsol) but they put priority 1) on the new releases I understand so it will come.
I have noticed that the simulations come the way/in the order you define them when setting up the model, by default, but you can set them up fully manually but then today you cannot move sequences up/down in the tree.
I have been told this is on the "list", hope it comes in the 4.0a version
If you know your particular "single" solve sequence try to unclick the physics Advanced automatic mode and define your solver sequence thereby the fields appear dynamically when you change the settings.
Good luck
Ivar
I have heard that COMSOL is working on it (I'm not Comsol) but they put priority 1) on the new releases I understand so it will come.
I have noticed that the simulations come the way/in the order you define them when setting up the model, by default, but you can set them up fully manually but then today you cannot move sequences up/down in the tree.
I have been told this is on the "list", hope it comes in the 4.0a version
If you know your particular "single" solve sequence try to unclick the physics Advanced automatic mode and define your solver sequence thereby the fields appear dynamically when you change the settings.
Good luck
Ivar