How Can I Resolve Memory Issues in COMSOL for a Complex 3D Model?

[juvel006]

I'm running out of memory on my model help! 3D not axisymmetric! Pictures of geometry and mesh attached. Any recommendations on how to make this possible? This is volumetric flow through a cylinder with a thin membrane attached that is porous and utilizes brinkman's equations.

 

[juvel006]

PS: ~ 156933 elements in this domain.

 

[Topher925]

You have two options, reduce the size of your mesh, or buy more RAM. You could also create a swap file but that will significantly increase the time required to solve the model.

 

[juvel006]

I would be willing to try a swap file due to the time I have. I'll start looking at that but are there any references on how to do this in COMSOL? Thanks!

 

[minger]

First, I'd HIGHLY recommend using an O-Grid hex mesh. There's no need for tets on a simple geometry like that. You're topology is a square(ish) rectangular prism through the center of the cylinder. Then just basically draw radial lines outward from the corners.

This will let you define exactly how you want the mesh. More importantly, you'll reduce the number of elements for the same quality mesh.

Next, as mentioned you can typically allow swap files or other memory management tools. These are sometimes runtime options, or specified in an input file somewhere. Do a search through the Comsol help to find that stuff.

Lastly, 160k elements is not a lot. If your machine can't handle that kind of run, then as Topher mentioned, get some more RAM. RAM is dirt cheap and you'd be surprised the increases in performance you can get.

 

[juvel006]

Any idea on how to do that in COMSOL? I'm very new (< 1 week) at using it. Thanks again

 

[minger]

You've been using Comsol for less than a week and you're solving a solution involving a porous membrane? I'd say you're out of your ability level already.

Either way, for a better mesh like I mentioned there are a couple methods. For the ANSYS analogy (since that's what I know), I would probably just create the model by hand. Then I could sweep the volumes as needed with proper inflation or spacing.

Alternatively we could bring the geometry into a mesher such as ICEM and do the work in there.

 

[Topher925]

Comsol doesn't have a good meshing tool. If you want a O-grid hex mesh you will probably have to create it manually or with another software.