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Hey all,

I'm working on a simulation of a microfluidic channel with a diluted species being introduced. Ideally I'd like to get this to a 3D transient solution and model the species fluid flow through the system, but right now I'm just trying to do it on 2D to begin with.

I had it working in Comsol 3.5a and formerly in Comsol 4a, but I just changed computer systems and now I can't get it working again. The simulation I'm looking to create will show the channel (in this case pretty much just a rectangle with a small obstacle), filled with water, that a new species will be introduced to and be able to view the dilution and flow of the species as a video. Currently what happens is that when I run the study there's no actual dilution or flow of the introduced species; the whole channel just goes from blue to red through the color spectrum, but there's no inlet where it starts or any differences throughout.

As I said, I've gotten it working before, but apparently I'm missing something now (which is odd since I'm fairly certain I'm using the exact same .mph file). I've uploaded it with this post so if anyone wants to see what I've got to get a better idea of what I'm talking about.

Much appreciation for any help or suggestions you can offer.

Also, if anyone can offer any suggestions on how to get a 3D transient microfludic simulation to work (something very similar to this only in 3D) I'd appreciate it as well. Right now all transient tests fail out saying they don't converge. Statis simulations will produce fluid velocity values for the water, though.