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Fine to coarse progressive mesh problem.

Posted Nov 15, 2011, 9:07 a.m. EST Computational Fluid Dynamics (CFD), Mesh Version 4.1 2 Replies

Michael Conneely
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Hello,

I have a two phase laminar fluid flow model with which I am trying to reduce computation time. To do this I have created a progressive mesh, starting with a fine mesh in the region of major interest which gets progressively coarser as you move away.

I have managed to crate the mesh I would like and the model runs perfectly apart from one issue. Transient Initialisation runs and I get an initial set of results for time 0, where the phase interface looks nice an narrow but after the first time step of the Time Dependent study the interface becomes very wide,as though thee was a very coarse mesh in that region.

I have attached a picture to highlight what I am trying to explain. The two left images show the progressive mesh and the width of the interface it gives and on the right just an example of when I make a fine mesh over the whole geometry where you can see a nice narrow interface boundary.

I would appreciate any help.

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2 Replies Last Post Nov 15, 2011, 9:43 a.m. EST
Ryan McDevitt
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Posted: 1 decade ago Nov 15, 2011, 9:15 a.m. EST
By default, COMSOL defines the interface thickness as h_max/2. If you've left this as your interface thickness, the coarser grid will drive that h_max larger, leading to a much wider interface.
By default, COMSOL defines the interface thickness as h_max/2. If you've left this as your interface thickness, the coarser grid will drive that h_max larger, leading to a much wider interface.
Michael Conneely
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Posted: 1 decade ago Nov 15, 2011, 9:43 a.m. EST
Thank you.

I knew it was something obvious I missed.
Thank you. I knew it was something obvious I missed.

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