Hi Gilian, I’m just guessing what the problem could be.. Have you tried not to set Dirichlet boundary conditions for the corner vertices? This can be tricky with the box method and its dual grid as you can’t control the flow over the sub control volume face adjacent to the corner vertex on the bottom and the top boundary if the corner is set to Dirichlet. This may cause the water to escape this weirdly through that single scvf.
Also, the outflow boundary condition only works, if you’re flow direction is always strictly outwards. So in the beginning it might not work out that well. You can use solDependentNeumann to weakly enforce any boundary condition, like a Robin/Cauchy-type. What’s on top of your domain conceptually? Best wishes Timo > On 13. Aug 2018, at 17:27, Schout, G. (Gilian) <[email protected]> wrote: > > Dear dumux-team, > > I hope you can help me solve a problem in my models that I’ve been trying to > figure out for some time now without success. Conceptually, I have been > modelling leakage of natural gas into a fully saturated unconsolidated > sedimentary aquifer. In the most basic version I use a 2D, 2p2c model where > methane enters the from the base of a fully saturated aquifer. The domain is > 120 by 60 m, and the injection occurs by way of a Neumann boundary between > x=30 and x=31 m. Besides this I have no flow boundaries at the top and > bottom, with an outflow boundary at the top for methane so that it can leave > the domain once it reaches the top (due to buoyancy). Then, to induce lateral > flow, I use a hydrostatic pressure distribution with a minor increase in > pressure towards the left of the domain, such that water flows to the right. > This distribution I have assigned as both the initial pressure and at sides > as dirichlet boundaries. The code can be seen on my GitLab of this version of > the model here > <https://git.iws.uni-stuttgart.de/gilianschout/CH4Leak/blob/master/2p2c/leak2p2c.hh>. > > Now the problem is that however I try to implement the lateral boundaries, I > always get unexpected velocity vectors around the corners of the domain as > you can see in this figure: > > <image002.jpg> > > Now this is not even that bad - in the middle of the domain the velocity > profile is as I would like it to be. However, when I increase the absolute > pressure in the domain, it becomes much worse. For example, here is the same > image for a depth of 240 m. > > <image005.jpg> > > This obviously influences the results of the simulation significantly. I have > been trying different solutions the last couple of days but haven’t been able > to put my finger on it. Presumably, there is some discrepancy between the > model calculated pressures and the pressures/densities set at the boundaries. > My hope is that someone in the team has perhaps run into similar issues and > has a solution. The goal is obviously to have strictly lateral groundwater > flow, without a vertical component (unless induced by the gas injection at > the bottom). > > Thanks in advance, kind regards, > > Gilian Schout | PhD Candidate | Faculty of Geosciences | Utrecht University | > +31 6 16523607 | [email protected] <mailto:[email protected]> > > _______________________________________________ > Dumux mailing list > [email protected] <mailto:[email protected]> > https://listserv.uni-stuttgart.de/mailman/listinfo/dumux > <https://listserv.uni-stuttgart.de/mailman/listinfo/dumux>
_______________________________________________ Dumux mailing list [email protected] https://listserv.uni-stuttgart.de/mailman/listinfo/dumux
