On Mon, Jun 26, 2023 at 11:44 AM Srikanth Sathyanarayana <s...@mpcdf.mpg.de> wrote:
> Dear PETSc developers, > > > I am currently working on a Gyrokinetic code where I essentially have to > implement a block structured grid approach in one of the subdomains of > the phase space coordinates. I have attached one such example in the x - > v_parallel subdomains where I go from a full grid to a grid based on 4 > blocks (divided along x direction) which is still Cartesian but > misaligned across blocks (the grid is a very coarse representation). So > the idea is to basically create a library for the existing solver and > try to implement the block structured grid approach which mainly > involves some sort of interpolation between the blocks to align the points. > > > I came up with an idea to implement this using DMDA. I looked into the > old threads where you have suggested using DMComposite in order to > tackle such problems although a clear path for the interpolation between > the DM's was not clarified. Nonetheless, my main questions were: > > 1. Do you still suggest using DMComposite to approach this problem. > Maybe > 2. Is there a way to use DMDA where the user provides the allocation? My > main problem is that I am not allowed to change the solvers data structure > I do not understand this question. > 3. I looked into VecCreateMPIWithArray for the user provided allocation, > however I am not very sure if this Vector can be used with the DMDA > operations. > It is unlikely. > Overall, I request you to please let me know what you think of this > approach (using DMDA) and I would be grateful if you could suggest me > any alternatives. > Can you give a short argument for your approach? For example, why would I want to use a multi-block approach instead of just using a single block? To save on storage? On computing? How much will you save? Why would I not want an unstructured grid covering the same area? Why would I not use structured-adaptive refinement (octree)? Thanks, Matt > Thanks and regards, > > Srikanth > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>