Hi All,
I need to solve the following 1D diffusion equation on domain x=[0,0.4] between time t=[0,2]:
w(u) du/dt = d^2u/dx^2
where w(u) = 1+184/u*(-1/log(u))^(4/3)
subject to the initial condition u(x,0) = 1e-4 and boundary conditions u(0,t) = 0.68 and du/dx(0.4,t) = 0.
This is how I set up the problem:
Model: coefficient PDE
Parameters: c = 1, da = w(u), all other coefficients = 0
Also set initial condition and boundary conditions accordingly.
Mesh: extremely fine
I then get the error message "error in user defined function: w" when I try to solve. However, the weird thing is if I increase the value of the initial condition to u(x,0) = 0.06 or above, the thing solves fine. It only crashes for small initial values...
Why do you think that is and what can I do to resolve this issue?
Many thanks!!
I need to solve the following 1D diffusion equation on domain x=[0,0.4] between time t=[0,2]:
w(u) du/dt = d^2u/dx^2
where w(u) = 1+184/u*(-1/log(u))^(4/3)
subject to the initial condition u(x,0) = 1e-4 and boundary conditions u(0,t) = 0.68 and du/dx(0.4,t) = 0.
This is how I set up the problem:
Model: coefficient PDE
Parameters: c = 1, da = w(u), all other coefficients = 0
Also set initial condition and boundary conditions accordingly.
Mesh: extremely fine
I then get the error message "error in user defined function: w" when I try to solve. However, the weird thing is if I increase the value of the initial condition to u(x,0) = 0.06 or above, the thing solves fine. It only crashes for small initial values...
Why do you think that is and what can I do to resolve this issue?
Many thanks!!