PETSc does take pains to keep it clean in Valgrind, to make it more useful ...
And yes there is tree structure to this error, and p4est is a tree code. Try with uniform bathymetry, maybe your mapping is messed up by some recording by p4est. On Wed, Jun 17, 2020 at 6:47 PM MUKKUND SUNJII <mukkundsun...@gmail.com> wrote: > No, I have not checked it using Valgrind. Perhaps it will help me trace > the problem. > > Regards, > > Mukkund > > On 18 Jun 2020, at 00:43, Dave May <dave.mayhe...@gmail.com> wrote: > > Is the code valgrind clean? > > On Wed, 17 Jun 2020 at 23:25, MUKKUND SUNJII <mukkundsun...@gmail.com> > wrote: > >> I agree with the structured nature of the noise. I did play around with >> the PetscFV implementation a bit to allow for the computation of different >> fluxes left and right side of every interface. >> >> Nevertheless it is indeed strange that the problem disappears when I use >> a PLEX dm. >> >> Regards, >> >> Mukkund >> >> On 17 Jun 2020, at 22:53, Dave May <dave.mayhe...@gmail.com> wrote: >> >> >> >> On Wed 17. Jun 2020 at 21:21, 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. >>> <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> >>> >>> >> The (wrong) result has seemingly a lot of structure. Have you verified >> your code using p4est is valgrind clean? This looks too much like a weird >> indexing bug for me to not ask this question. >> >> Thanks, >> Dave >> >> >> 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 >>> >>> >> >
