Discussion Forum

According to what I understood from your problem set-up, I attach here my solution. Note that substrate is initially everywhere at concentration S but is consumed in the reaction. The distances are so small that the entire space is filled with product rather quickly.

BR
Lasse

Hi Lasse,
I cant open the file, its in later version.

Which version do you have?

I have COMSOL 4.4

I made a report of the model. It is not very clear, if I may say so, but I have two variables c1 (product) and c2 (substrate) which diffuse in the entire domain [0,L]. The reaction takes place in the domain [0,d]. At x = 0 and x = L I have No Flux condition. At point x = d no BC is needed at all, neither another separate Convection and diffusion node. I deactivated convection, so it does not appear at all in the node.

Reaction Rsp = Vmax*c2/(Km + c2); it must be defined as a variable under Component Definitions, not global. I deleted all variables under Global Definitions.

I used time stepping 0,10^{range(-6,0.2,0)} because the reaction rate is at highest in the beginning.

Wish this helps
Lasse

I need at x=d there should be a flux(P) and concentration(P) continuity. I don't need a boundary condition for that?

No. Comsol assumes continuity of fluxes and concentrations unless you deliberately wish to change it. That could be due to, say, partitioning between the aqueous and organic phases.