Diffusion through membrane, which boundary condition to implement?

[baseball1234]

Hi, I am solving the diffusion equation using explicit finite difference to model the diffusion of an analyte through a membrane. I am interested in the concentration of the analyte on the other side vs time elapsed. On one side of the membrane is an initial concentration, which I am implementing as a Dirichlet boundary condition, and the other is zero concentration of the analyte, in a blank solution. The initial condition of this other side would be 0, however I am unsure what the boundary condition would be. My first assumption would be a Neumann zero-flux boundary condition, however I don't know if this is correct. Any help on this would be great, thanks.

 

[meldraft]

I'm not a chemical engineer, so I don't really know the physics of your problem, but if you want your solution to actually flow through that boundary, then you can't have a Neumann condition. If it is indeed supposed not to flow through it, then I would say that you are correct