Discussion Forum

Posted: 1 decade ago Mar 1, 2012, 5:50 p.m. EST

Hi from my understading, none in your case. With "solid" physics or TS thermal stress it's the "spatial frame" that takes care of the "growth" of your material The ALE is used for mixing two physics that intract over a change in geometry of one (i.e. solid) that interacts on the geometry of the other i.e. fluid. Lets say a solid plate bending under a pressure load, below the plate is a thin air gap with below a fixed boundary (GND) (see the simple capacitor model) the air gap is modelled with ALE and the mesh deformation of the ALE is driven by the deformation of the spatial frame of the SOLID. DG deformed geometry is typically used if you want to scale your geometry during the solving process (i.e. change the thckness of aI beam to find the optimal strength -- Good luck Ivar

Posted: 1 decade ago Mar 2, 2012, 11:18 a.m. EST

Hello Ivar: Thanks for the quick response. I was afraid that I would confuse the issue by giving thermal expansion as an example. My question is more general. What if expansion (not just deformation) is due to some other physical phenomenon. Like the expansion of a bubble or balloon due to generation of fluid/gas inside. As I understand it from the user's guide, in moving mesh option volume is constant, but in deformed geometry it can add or subtract. Thanks sushant

Posted: 1 decade ago Mar 3, 2012, 4:15 a.m. EST

Hi indeed DG can be seen as a deformation Xg,Yg,Zg taking place between the geoemtrical entities and the material frame used for the FEM reference, while ALE is a deformation "after" the material reference. It's not very clean, but it is "may way" of seeing it, I agree some clear simple fomulas in the doc to show the chain XYZ_G XYZ XYZ_M xyz or hwatever way it truely goes could be nice. I'm finding part of the reply (most the mathematics clearly explained, but not the full chain as per COMSOL) in the new book of EB.Tadmor. RE.Miller, RS.Elliot "Continuum Mechanics and Therodynamics", CUP 2012, stil lstudying it ;) -- Good luck Ivar

Posted: 1 decade ago May 22, 2013, 3:27 a.m. EDT

[QUOTE] Hi indeed DG can be seen as a deformation Xg,Yg,Zg taking place between the geoemtrical entities and the material frame used for the FEM reference, while ALE is a deformation "after" the material reference. It's not very clean, but it is "may way" of seeing it, I agree some clear simple fomulas in the doc to show the chain XYZ_G XYZ XYZ_M xyz or hwatever way it truely goes could be nice. I'm finding part of the reply (most the mathematics clearly explained, but not the full chain as per COMSOL) in the new book of EB.Tadmor. RE.Miller, RS.Elliot "Continuum Mechanics and Therodynamics", CUP 2012, stil lstudying it ;) -- Good luck Ivar [/QUOTE] Hi Recently I want to use Comsol to deal with a deformation problem. In my model, the object is a highly compressible porous medium which may be seen as a binary mixture of a viscous fluid constituent and a elastic solid constituent. And I want to use the PDE interface to enter the governing equations. I'd like to see how the medium recovers after squeezed. Which one do I use, Deformed geometry or moving mesh?

Posted: 9 years ago Jan 6, 2016, 4:10 a.m. EST

Hi Sir I have something to ask regarding to deformed geometry on chemical vapor deposition. Can you please explain to me on how to use this deformed geometry on my application? In this model, I want to simulate to obtain graphene layers, and I heard that by using deforming mesh coupled with diffusion transport model, the problem can be solved. To clarify this, I want to make the precipitated carbon atoms can cause a movement in +y-direction to the interface between Pd film domain and N2 domain. I hope you can answer my question. Thanks.