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"ALE" VS "Spatial Frame" equivalent for this problem?
Posted Mar 15, 2011, 10:12 a.m. EDT Structural Mechanics Version 4.1 1 Reply
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Hi!
I notice that there are many interesting discussions about moving mesh.
Now I have a simple question about ALE and different frames in Comsol 4.1.
Say that want to solve a Darcy's law equation based on the deformed structure mesh. It's similar to solve a heat problem based on the deformed structure.
Two ways to solve this in V4.1.
1. Checked the option "displacements control the spatial frame" (it's checked by default). Solve the solid phase in the material frame, and select the frame type of Darcy's law module to "Spatial frame".
2. Use ALE. Unchecked "displacements control the spatial frame" in solid structure module. Add moving mesh module. Selected Darcy's law frame type to Spatial frame (I was expecting "ALE frame" as version 3.5a, but the name is still "Spatial frame"), ALE displacement set to the displacement of the solid phase.
I tested above two method, they give almost identical results.
But theoretically they should be equivalent?
In this case, they we don't even need ALE for this kind of problem any more? Then where is ALE needed? For extremely large deformation where remesh is needed?
Thanks a lot.
XLi
I notice that there are many interesting discussions about moving mesh.
Now I have a simple question about ALE and different frames in Comsol 4.1.
Say that want to solve a Darcy's law equation based on the deformed structure mesh. It's similar to solve a heat problem based on the deformed structure.
Two ways to solve this in V4.1.
1. Checked the option "displacements control the spatial frame" (it's checked by default). Solve the solid phase in the material frame, and select the frame type of Darcy's law module to "Spatial frame".
2. Use ALE. Unchecked "displacements control the spatial frame" in solid structure module. Add moving mesh module. Selected Darcy's law frame type to Spatial frame (I was expecting "ALE frame" as version 3.5a, but the name is still "Spatial frame"), ALE displacement set to the displacement of the solid phase.
I tested above two method, they give almost identical results.
But theoretically they should be equivalent?
In this case, they we don't even need ALE for this kind of problem any more? Then where is ALE needed? For extremely large deformation where remesh is needed?
Thanks a lot.
XLi
1 Reply Last Post Mar 15, 2011, 11:23 a.m. EDT
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Posted:
1 decade ago
Hi
I would also say ALE is for "large displacements", specially if you do not want to model with physics for one or several of the domains.
If you use the spatial frame in solid/structural, you need to define a structural "liquid" or "gas" for many cases. This is possible, but not always correct either. ALE is nothing else (in principle) than a mesh of springs deforming but without acting on the boundaries via pressure or other physical effects, only looking into dformations.
I believeyou would also say that there are differences etween both methods, even if subtle
Then it's a question of "what" precision you requst or expect, do not overdo it, its not worth the calculation time ;)
--
Good luck
Ivar
I would also say ALE is for "large displacements", specially if you do not want to model with physics for one or several of the domains.
If you use the spatial frame in solid/structural, you need to define a structural "liquid" or "gas" for many cases. This is possible, but not always correct either. ALE is nothing else (in principle) than a mesh of springs deforming but without acting on the boundaries via pressure or other physical effects, only looking into dformations.
I believeyou would also say that there are differences etween both methods, even if subtle
Then it's a question of "what" precision you requst or expect, do not overdo it, its not worth the calculation time ;)
--
Good luck
Ivar