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multiphysics on COMSOL 4

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Hi all,

The problem I have is with using COMSOL 4.0. I have two coupled physics (poisson and carrier continuity). The first physics (poisson) is defined on an entire geometry, while the second physics (continuity) is only defined on a few subdomains. In Comsol 3.4 I could simply uncheck the "active in this domain" for the continuity equation in those domains where it is not defined. In COMSOL 4, I tried two options:

1) adding one physics module with my two dependent variables as the solution vector "u", and just setting the coefficients for the undefined domain to zeros. As I expected, this method resulted in a singular matrix which means that Comsol expects that when you define all your dependent variables in one interface, then these variables should all be defined on the same domains.

2) one physics interface for poisson which is valid in all domains, and another physics for continuity which is only valid on some domains. However, I need them solved simultaneously, and the study only allows me to choose one physics interface !!

Any ideas on how I can overcome this problem ? Thank You.

0 Replies Last Post 4 nov 2010, 12:58 GMT-4
COMSOL Moderator

Hello Waleed Shinwari

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