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unstructured and structured mesh in comsol
Posted Aug 29, 2015, 11:46 p.m. EDT Low-Frequency Electromagnetics, Mesh Version 5.0 1 Reply
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Dear friends
which kind of mesh could lead better results?
someone said that unstructured mesh is better in comsol, which is different from FLUENT or some other software.
If this concept is correct, why?
which kind of mesh could lead better results?
someone said that unstructured mesh is better in comsol, which is different from FLUENT or some other software.
If this concept is correct, why?
1 Reply Last Post Aug 30, 2015, 11:23 a.m. EDT
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Posted:
9 years ago
Hi
I do not believe there one is better than the other, it all depends on what you are modelling.
COMSOL used discretization polynomials on-top of the standard elements, therefore tetrahedral elements work "better" here, than in older FEM codes, with other underlying hypothesis. COMSOL has put meshing and the elements where they should be: a mathematical discretization of the geometrical space, such to resolve correctly the dependent variables and their variations of the differential equations you want to solve.
If you are a beginner (with COSMOL) use the default mesh settings, once you master them, play with the density: normal, fine, finer ... and check what is going on: are your results "better" ( 1) be sure you know what is "better" and 2) these effects will be different for each of your models), you need to learn why, be curious, try out "toy-models" to understand the relation to mesh density, discretization order and coherence of the results, all depending on the type of equations you solve: Poisson, diffusion, wave, NS ...
I use generally structured meshes for very anisotropic shaped geometries, and when the dependent variables do not change much (small gradients) with respect to the "thin" thickness dimension, and also often for 2-3D problems with 1-2D-Axi-symetric geometry and BC conditions, as here mostly the "phi" variation of your dependent variables are small and you are less disturbed by the radial dependence on the mesh size change, layer by layer, i.e. on axis lens and mirror opto-mechanics
--
Good luck
Ivar
I do not believe there one is better than the other, it all depends on what you are modelling.
COMSOL used discretization polynomials on-top of the standard elements, therefore tetrahedral elements work "better" here, than in older FEM codes, with other underlying hypothesis. COMSOL has put meshing and the elements where they should be: a mathematical discretization of the geometrical space, such to resolve correctly the dependent variables and their variations of the differential equations you want to solve.
If you are a beginner (with COSMOL) use the default mesh settings, once you master them, play with the density: normal, fine, finer ... and check what is going on: are your results "better" ( 1) be sure you know what is "better" and 2) these effects will be different for each of your models), you need to learn why, be curious, try out "toy-models" to understand the relation to mesh density, discretization order and coherence of the results, all depending on the type of equations you solve: Poisson, diffusion, wave, NS ...
I use generally structured meshes for very anisotropic shaped geometries, and when the dependent variables do not change much (small gradients) with respect to the "thin" thickness dimension, and also often for 2-3D problems with 1-2D-Axi-symetric geometry and BC conditions, as here mostly the "phi" variation of your dependent variables are small and you are less disturbed by the radial dependence on the mesh size change, layer by layer, i.e. on axis lens and mirror opto-mechanics
--
Good luck
Ivar