Hi Jamie, The simplest way might be just to take a basic grid and just "switch off" the simulation outside of the black zone. This can be achieved by including a transient term in the equation and setting the coefficient to be large in the white zone and zero or something small in the black zone. That would be an easy first attempt to solve the problem. Of course this approach has a lot of redundancy, but would be a good first step. You may have to interpolate the A and B values to a coarser grid for this approach to be feasible.
It is possible in FiPy to combine grid's into odd shaped non-rectangular grids. You could do this with say 20 or 30 smaller grids to better isolate the black region. I still think that you want to interpolate the values of A and B so you have control over the grid density. You don't necessarily need a grid density at the sample density. Also, you will still need the trick with the Transient Term. Furthermore, the grids must align and not overlap. It will take quite a bit of programming to set this up so that you have control over the grid density and the number of subgrids to isolate the black region. Gmsh will probably be happy meshing the black region, but will probably use triangles rather than a grid. To summarize use the first approach to make things work right and then refine with the second approach. Hope it helps. On Tue, Jun 7, 2016 at 1:46 PM, James Pringle <jprin...@unh.edu> wrote: > Dear mailing list & developers -- > > I am looking for hints on the best way to proceed in creating a > grid/mesh for a rather complex geometry. I am just looking for which method > (Gmsh or something else?) to start with, so I can most efficiently start > coding without exploring blind alleys. > > I am solving an elliptic/advective problem of the form > > 0=J(Psi,A(x,y)) + \Del(B(x,y)*\Del Psi) > > where Psi is the variable to solve for, and A(x,y) and B(x,y) are > coefficients known on a set of discrete points shown as black in > https://dl.dropboxusercontent.com/u/382250/Grid01.png . The black appears > solid because the grid is dense. > > The locations of the points where the coefficients are known define the > grid. The number of points is large (911130 points) and they are evenly > spaced where they exist. Note that there are holes in the domain that > represent actual islands in the ocean. > > I am happy to keep the resolution of the grid/mesh equal to the spacing of > the points where the coefficients are known. > > What is the best way to approach creating a grid for this problem? I would > love code, of course, but would be very happy with suggestions of the best > way to start. > > Thanks > Jamie Pringle > University of New Hampshire > > _______________________________________________ > fipy mailing list > fipy@nist.gov > http://www.ctcms.nist.gov/fipy > [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ] > -- Daniel Wheeler _______________________________________________ fipy mailing list fipy@nist.gov http://www.ctcms.nist.gov/fipy [ NIST internal ONLY: https://email.nist.gov/mailman/listinfo/fipy ]
