Re: robin boundary condition

2014-06-27 Thread Daniel Wheeler
Hi Rose, I was trying to debug this and it seems like there is an inconsistency between the left hand boundary and the analytical solution. By my calculations A~1 and B~0, that makes the gradient of the line about 1, yet the left hand boundary condition expects a gradient of about 0.0666 (if C

Re: robin boundary condition

2014-06-27 Thread yuan wang
Hi Daniel, Thanks for your response. The left side boundary condition is the first boundary condition shown below. So, what I did is to express dC/dz at z=0 as beta*(C-Cw)/D to set the constraint for the gradient on the left side. I learned this from one of the examples (Convection.Robin) in the

Re: robin boundary condition

2014-06-27 Thread Guyer, Jonathan E. Dr.
What Daniel is saying is to set the FiPy solution aside for the moment. Your analytical solution does not appear to be consistent with your boundary condition: A = beta*(Cl-Cw)/(D+beta*L) \approx 1 B = Cl-A*L \approx 0 Canal = A*zc+B \approx zc (\partial Canal /

Re: robin boundary condition

2014-06-27 Thread yuan wang
Hi Daniel and Jonathan, I used Matlab's pdepe function and got numerical solution that is close to my analytical solution. I've attached the code for your information. Best regards, Rose On Fri, Jun 27, 2014 at 2:10 PM, yuan wang rose.w...@tufts.edu wrote: Hi Daniel and Jonathan, I double