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Problems with using deriviative opertaor (4.3.0.151)

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I'm using the general PDE module coupled with creeping flow. The PDE solves the electrostatics problem (Laplace equation) and finds the electric potential (phi) everywhere.
I'm trying to put in a slip velocity at the walls defined by d(((phi-v1)*conj(phi-v1)),x)
where phi is the electric potential found in the first step and v1 is a constant value.
For some reason when computing this expression equals zero and gives no slip velocity.
I've tried to plot this expression and got something different than zero.
what could be the problem?


0 Replies Last Post 26.02.2014, 03:50 GMT-5
COMSOL Moderator

Hello Dana Ben Bassat

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