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How to solve PDE with dependent variable?

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Hi, all,

I am trying to solve two PDEs regarding phase field.

The common PDEs include one equation related to phi and another related to chemical composition (c). Here, I non-dimensionlized the composition by using U=U(c,phi), so U is a function related to c and phi.

Now the question is how I set U expression. Because when I set U as a variable with the expression, when I tried to solve the 2nd PDE, there were two problems. Fristly, since I have not defined c, the U expression is actually in orange color (warining). Secondly, since I already define U as a variable, while in the PDE, I have to set U as the dependent variable to solve PDE, and the error (duplicate variable) shows.

So how do I set U to let the PDE solver knows that U is a function of phi and c, and I am actually trying to solve c.

Thanks, Xing


0 Replies Last Post Mar 8, 2018, 2:01 a.m. EST
COMSOL Moderator

Hello Xing Zhang

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