Hello, I am modeling a parallel plate reactor with a porous catalyst layer attached. I have already built my reaction model using Reaction Engineering module. I then generated a space-dependent model from that. I am able to successfully model the fluid flow using the free and porous media module in COMSOL. However, I am not able to combine that with the transport of dilute species module and chemistry module to get the final result. I keep getting an error "Singular Matrix" which I do not know how to even correct. I also greatly removed the complexity of the problem by assuming it only occurs in one single region and was able to successfully to simulate both flow and concentration profiles. However, as I said, whenever I use two domains, I always get the error. Please help me to figure out what is wrong with my model. I am also attaching the .mph file.
P.S Please note that all the reactions only occur in region 2 ( the small catalyst layer). A and P are the bulk species which can be present in both regions but all other six species should only present in region 2 ( the porous region). To satisfy that condition, I have used a fulx discontinuity at the shared boundary and equated the fluxes of all those 6 species to zero.
thanks Widitha