Discussion Forum

Hi,

I am trying to model a completely electroosmotic (EO) flow in a microchannel where a miscible displacement of oil with water occurs. I believe all other set ups are correct but there is probably something wrong with the way I have st up my boundary condition (BC) which I need help with. In my model, I have used the creeping flow, transport of diluted species and electric current physics. In the creeping flow physics, I have assigned an EO velocity to the wall based on the Smoluchowski's equation and with the assumption of a small and negligible EDL, while the inlet and outlet BC were set to open boundary. In the electruc current physics, I have assigned voltages to the inlet and outlet, while the walls are electrically insulated. In the transport of diluted species physics, there is no flux at the walls while the inlet and outlet have fluxes (General inward flux for the inlet and external convection for the outlet). After running the model, I am surprisingly getting a parabolic velocity flow profile even though I have not prescribed any pressure or velocity at the inlet or outlet of my system. I would normally expect to see a plug flow profile, with a constant velocity along the channel. I am not sure exactly what to do in this case and I would appreciate any help that I can get. Thank you.