Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

High Aspect Ratio Meshes

Please login with a confirmed email address before reporting spam

Hi COMSOL'ers,

I am modeling a problem in the creeping flow module and having issues with meshing. The problem is composed of two "nearly" touching spheres of equal radius surrounded by fluid. I am interested in what's happening between the spheres (high pressure and velocity gradients), so I need a fine mesh here. The difficulty is that the gap between the spheres is ~Radius/10^4, so I need very small elements that grow to larger elements away from the gap.

My geometry has a small cylinder in the region between the spheres where I built the fine mesh with swept quadrilateral elements of "size" separation*5 and "distribution" of 2. This results in 2 elements across the separation and a sweeping element size of separation*5. The simulation takes ~1hr to run with an iterative multigrid method and uses ~4GB ram in the process. Now, the results aren't what I'm expecting and I'm getting ~8% error in my solution, compared to the analytic solution. I tried increasing the "distribution" to 4 or even 3 elements across and the ram increases to nearly 20GB, even though this isn't a significant jump in DOF and the solving times would be unrealistic.

Does anyone have a recommendation on different types of elements to use or other methods of meshing? Also, I'm using P2+P1 discretization.


Thank you everyone!

0 Replies Last Post 22.09.2016, 13:44 GMT-4
COMSOL Moderator

Hello Adam Woodman

Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.

If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.