Hi Etienne, I think an outflow boundary condition will only work correctly if the phase that is leaving the domain is perfectly mixed, i.e. there is only transport perpendicular to the outflow boundary face. You might be able to solve your problem by appending a kind of pipe to your outflow. This way you are able to use the outflow condition at the end of the pipe. I am not 100% sure whether this will work.
Best regards Georg -----Ursprüngliche Nachricht----- Von: Dumux [mailto:dumux-boun...@listserv.uni-stuttgart.de] Im Auftrag von Etienne Ahusborde Gesendet: Dienstag, 21. November 2017 13:50 An: DuMuX User Forum; Mohamed Id Moulay Betreff: [DuMuX] Outflow boundary conditions Dear DuMuX users, With my colleagues we are working on an example of reactive flow in porous medium with an outflow boundary condition. To emphasize our issue, we have considered a simpler problem using the 1p2c model where a component X1 is injected in pure water (see the enclosed figures geometry.png and permeability.png). There are two zones of injections named Inflow1 and Inflow2 (where a flux is imposed and a dirichlet boundary conditions is imposed for the concentration of X1) and an outflow zone. The remaining boundaries are impermeable. The pictures X1cell.png and X1box.png depict the concentration of the component X1 after 125s of injection respectively with the cell centered and box schemes. We can see at the outflow the presence of two pikes at the border between the outflow and the impermeable zones. These pikes are unphysical since the maximum value of the concentration should be equal to the value of the dirichlet condition (that is 0.3). We would like to know is somebody ever had and fixed this problem? Thanks in advance. Best regards Etienne _______________________________________________ Dumux mailing list Dumux@listserv.uni-stuttgart.de https://listserv.uni-stuttgart.de/mailman/listinfo/dumux