Greeting, >> transferring from one grid to another. Here it looks like it is artificially >> diffusive, but I do not >> see a reason for this pattern if you did the refinement initially, and not >> with p4est, since then the base grid is the same as the Plex. Is that what >> your code does?
I am not sure how to differentiate the refining method. For the results that does not have this pattern, I provide the following command line options: -dm_type plex -grid_size 32,32. For the one that shows this odd pattern, the command line options I provide are: -dm_type p4est -dm_refine 5. > Also, when using p4est, the orientation of the cells are different than the > one generated when refining with DMPlex alone. I would double-check the code > if you are not making any assumption ons it I suppose this could indeed be the case as I do fiddle around with the Riemann solver interface in petscfv.c Regards, Mukkund Sunjii Sent on the go. > On 18 Jun 2020, at 10:40 PM, Stefano Zampini <stefano.zamp...@gmail.com> > wrote: > > > Also, when using p4est, the orientation of the cells are different than the > one generated when refining with DMPlex alone. I would double-check the code > if you are not making any assumption ons it > >> Il giorno gio 18 giu 2020 alle ore 23:24 Matthew Knepley <knep...@gmail.com> >> ha scritto: >>> On Wed, Jun 17, 2020 at 3:21 PM MUKKUND SUNJII <mukkundsun...@gmail.com> >>> wrote: >> >>> Yes, precisely! I am not sure how I can replicate using the original >>> version of ex11.c because it does not support bathymetry. >>> >>> Regardless, to demonstrate the discrepancy, I have uploaded three plots. >>> The scenario is a lake at rest. Essentially, you have a varying bathymetry >>> but a level water surface. If the model is well balanced, then the water >>> surface height must not change. The description of the files are below >>> >>> 1) Bathymetry.png : It shows you the bathymetry profile (z(x)) and the >>> water surface height (H = h+z(x)) at t = 0. >> >> Hmm, that does look like a bug. The purpose of TransferVec is to preserve >> moments when transferring from one grid to another. Here it looks like it is >> artificially diffusive, but I do not >> see a reason for this pattern if you did the refinement initially, and not >> with p4est, since then the base grid is the same as the Plex. Is that what >> your code does? >> >> Thanks, >> >> Matt >> >>> <Bathymetry.png> >>> >>> 2) Plex.png : This is the water surface height after 1 time step (0.007055 >>> sec) and the dm type is Plex. As you can see, the water surface height is >>> undisturbed as expected. >>> <Plex.png> >>> >>> 3) P4est.png : This is the result after 1 time step (same final time) if I >>> set the dm type as p4est. The noise is in the order of 1e-3 to be a little >>> more specific. Since its not specifically at the boundaries and more or >>> less spread throughout, it could indeed be noise introduced. But of course >>> I could be wrong. >>> <p4est.png> >>> >>> Maybe this paints a better picture. >>> >>> Regards, >>> >>> Mukkund >>> >>> For your reference, the Riemann Solver is a modified version of the HLL >>> solver: A simple well-balanced and positive numerical scheme for the >>> shallow-water system by Emmanuel Audusse, Christophe Chalons, Philippe Ung. >>> (https://www.intlpress.com/site/pub/files/_fulltext/journals/cms/2015/0013/0005/CMS-2015-0013-0005-a011.pdf) >>> >>>> On 17 Jun 2020, at 20:47, Mark Adams <mfad...@lbl.gov> wrote: >>>> >>>> So you get this noise with a regular grid in p4est. So the same grid as >>>> will Plex, and you are not getting the same results. >>>> >>>> I don't know of any difference from p4est on a non-adapted grid. Can you >>>> reproduce this with ex11? >>>> >>>> Matt and Toby could answer this better. >>>> >>>> >>>> On Wed, Jun 17, 2020 at 1:33 PM MUKKUND SUNJII <mukkundsun...@gmail.com> >>>> wrote: >>>> Greetings, >>>> >>>> I am a master’s student working on the shallow water model of the TS >>>> example 'ex11.c' as part of my thesis. Therefore, I am working with >>>> DMForest for the implementation of adaptive grids. I have a question and >>>> an observation. >>>> >>>> I am trying to find relevant information about interpolation that takes >>>> place through the routine DMForestTransferVec. Perhaps it could be my >>>> inability to find it, but I am unable to locate the implementation of the >>>> routine >>>> >>>> (forest->transfervec)(dmIn,vecIn,dmOut,vecOut,useBCs,time). >>>> >>>> Any information on this particular routine is highly appreciated. >>>> >>>> Furthermore, I have developed a well balanced Riemann Solver that includes >>>> topography in the model. In the process of testing both the non-adaptive >>>> and adaptive version, I found that my results differed when I changed the >>>> type of DM. For instance, when I run a scenario in a fixed, non-adaptive >>>> grid with a DM of type 'P4est', I find that the well balanced nature is >>>> lost due to small perturbations all across the domain. However, this does >>>> not occur when I use a DM of type ‘plex’. Is there a radical change in the >>>> routines between the two DM’s? This is not as much of a question as it is >>>> an observation. >>>> >>>> Thank you for all of your suggestions! >>>> >>>> Regards, >>>> >>>> Mukkund >>>> >>>> >>> >> >> >> -- >> 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/ > > > -- > Stefano
