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.

slip length (Navier bc) with iterative solver in Stokes equation

Please login with a confirmed email address before reporting spam

Dear Comsol community,

I want to solve the Stokes equation with a Navier bc on one boundary.
(slip velocity = sliplength * du/dn, with n the normal on the boundary
and u the tangential flow velocity)

This works fine with a direct solver, but I did not find any way to get an
iterative solver to converge (2d or 3d).

Neither as viscous slip, nor a "manual" w=wr*sliplength at the boundary works.
It either does not converge or gives errors like "NaN found" or "Inf found".
I tried most iterative solver combinations and studied the Preconditioner Selection Guidelines.

Do you know how to get the Navier bc (special case of Robin bc?) to
work with an iterative solver? Thanks for your help.

EDIT: The default solver for linear elements does work. But since I am interested in forces on boundaries,
I need at least P2+P1 discretization.

Greetings,
Andreas

0 Replies Last Post 21 gen 2015, 04:57 GMT-5
COMSOL Moderator

Hello Andreas Meyer

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.