Hi Wolfgang, Thank you for the kind reply.
Memory pressure is the reason I turn to step-40. What I'm trying to figure out is that: instead of one layer of ghost cells, is it possible to have multiple layer ghost cells within the framework of step-40? Besides the information (solution) on the adjacent cells on the neighbor processor, my application probably asks for information on other cells owned by the neighbor processor, but not immediately adjacent to any cell owned by the current processor. The other way to see this is that my application may require information on all active cells within a coarser level cell that is not owned by the current processor, but adjacent to cells owned by the current processor. Thank you. Best regards, Xin On Tue, Nov 29, 2011 at 8:26 PM, Wolfgang Bangerth <[email protected]>wrote: > > > I'd like to use the nice dealii framework of parallel computing with > > multiple processors using distributed memory, which is illustrated in > > step-40. It is clear that we can recover the solution on the processor > > owned cells as well as on a layer of ghost cells. My question is whether > > dealii has some functionalities to reconstruct the solution on the entire > > distributed triangulation, including artificial cells, > > The information is of course there, distributed across all processors. But > it's not on every single processor, for a simple reason: the framework is > designed for the case where no single processor has enough memory to store > the > entire solution. The existence of artificial cells is one case in point: > artificial cells on one processor are not necessarily locally-owned cells > on > another processor; in general, the global mesh will consist of the > children/grand children/... of artificial cells on one processor. > > If you want to work in a framework where every processor has access to all > the > information, take a look at steps 17 and 18. > > All of this aside: If you tell us what you want to do, maybe we can come up > with a better solution! > > Best > W. > > ------------------------------------------------------------------------- > Wolfgang Bangerth email: [email protected] > www: http://www.math.tamu.edu/~bangerth/ >
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