Dear developers, I am trying to solve the following diffusion PDE with fipy:
S(h) * dh/dt = d/dx(T(h)*dh/dx) + P S and T are both nonlinear functions of h. (There is no closed analytical form to express them, but they could be parameterized somehow, e.g., S(h) = a*exp(b*h)) Reading the docs and following the examples, it seems to me that TransientTerm(coeff=S) would not do the job in FiPy, since this corresponds to d(S*h)/dt. One idea is to write the left hand side of the equation above as: S*dh/dt = d(S*h)/dt - h*dS/dt. Then, the equation would look like so: d(S*h)/dt = d/dx(T(h)*dh/dx) + P + h*dS/dt And this new version of the equation would be implemented as follows: TransientTerm(coeff=S) == DiffusionTerm(coeff=T) + P + ImplicitSourceTerm((S - S.old)/dt) However, this new term makes the equation very unstable. Is this the right way to approach this problem in FiPy? Are there any alternatives? Thanks for your help. Best regards, Iñaki
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