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