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How to implement this trick (dealing with large mesh deformation in ALE) ?

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In comsol users' guide, in "Limitation of the ALE Method", p555 (v4.0), p647(v4.1), an trick was given to deal with large mesh deformation, i.e., introducing extra boundaries with explicit deformation inside the domains. But I don't understand it, can anybody explain this trick in detail, it would be better if you can give an example. Thank you!

1 Reply Last Post 2011年3月8日 GMT-5 15:39
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2011年3月8日 GMT-5 15:39
Hi

Often, when using ALE you have a small object moving with a large volume of fluid around.

This means often that the moving mesh is highly deformed very locally around the object, even such that you get inverted elements in this region, but it hardly defoms some short distance from the flexible body.

Ideally you should try to get the mesh to deforme rather regularly all around.

So all depending on the model symmetry, you can sometimes add some intenal boundaries (fixed or moving with the some flexing domain/boundary) such to better distribute the mesh deformatin (reduce the mesh deformation gradient). That is basically the principle of the "trick"

--
Good luck
Ivar
Hi Often, when using ALE you have a small object moving with a large volume of fluid around. This means often that the moving mesh is highly deformed very locally around the object, even such that you get inverted elements in this region, but it hardly defoms some short distance from the flexible body. Ideally you should try to get the mesh to deforme rather regularly all around. So all depending on the model symmetry, you can sometimes add some intenal boundaries (fixed or moving with the some flexing domain/boundary) such to better distribute the mesh deformatin (reduce the mesh deformation gradient). That is basically the principle of the "trick" -- Good luck Ivar

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