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Flux Boundary Condition in Equation Based Modelling

Posted Mar 5, 2017, 4:07 p.m. EST Computational Fluid Dynamics (CFD), Porous Media Flow, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 5.2 0 Replies

Alireza Talebi
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There are different ways to implement the governing equation in COMSOL using the coefficient form of PDE in mathematical interface. For example, one can use the “αu” term to define convection in domain while β=0 in the “ β.∇u” term; or the other way around.
But when it comes to define the flux boundary condition, it seems that it is important how the PDE was implemented (i.e., in terms of which term is used). Because according to flux BC in COMSOL (-n .(-c∇u-αu+γ)=g-qu), having the convection term or not on the left hand side seems to have impact on the defined boundary condition (right hand side).
So here are my questions:
Dose the way the governing equation implemented have impact on how COMSOL interpret the BC?
How dose COMSOL implement flux BC?
I am totally confused with the flux BC and could not find a good explanation on how this sort of BC should be applied in COMSOL equation based modules.
Any one can help?
0 Replies Last Post Mar 5, 2017, 4:07 p.m. EST
COMSOL Moderator

Hello Alireza Talebi

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