<div dir="ltr">Heeho,<div><br></div><div>Based on the equations shown in the papers Glenn pointed out, it looks like you're solving at least a two-field problem (with elliptic operators on the diagonals) that needs to be approximated with a schur complement. If so, then naively applying *any* preconditioner (ilu, AMG, etc) on the entire NxN system (where N >= 2) is never going to work. Did you try using the PCFieldSplit (with the multiplicative option) and apply these different black-box preconditioners on the diagonal blocks? Because if that doesn't work, then you really need to do the schur complement, and the particularly strategy they mentioned (taking the diagonal of the A11 block) to approximate the Schur complement matrix can be done via the "selfp" option in PETSc.</div><div><br></div><div>Justin</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 6, 2019 at 2:11 PM Park, Heeho via petsc-dev <<a href="mailto:petsc-dev@mcs.anl.gov">petsc-dev@mcs.anl.gov</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Hello,<br>
<br>
It looks like pARMS does not work. Are there any other ILUT preconditioner external packages available that are not listed?<br>
<br>
Thank you,<br>
<br>
- Heeho Daniel Park<br>
<br>
On 3/6/19, 10:59 AM, "Park, Heeho" <<a href="mailto:heepark@sandia.gov" target="_blank">heepark@sandia.gov</a>> wrote:<br>
<br>
Jed, thank you for your perspective. I can certainly try BoomerAMG on our problem. I'm also going to try pARMS for variance of ILU.<br>
Glenn, I think I need to first work on restructure of the matrix and then scaling.<br>
<br>
- Heeho Daniel Park<br>
<br>
On 3/5/19, 11:34 PM, "Jed Brown" <<a href="mailto:jed@jedbrown.org" target="_blank">jed@jedbrown.org</a>> wrote:<br>
<br>
Yeah, I wouldn't get bogged down in that. I would work on the good<br>
methods and then use as a reference those components without the<br>
composition. For example, you might use Hypre's BoomerAMG inside a<br>
composed preconditioner. You could run it on its own to show that the<br>
chosen structure was important.<br>
<br>
"Hammond, Glenn E" <<a href="mailto:gehammo@sandia.gov" target="_blank">gehammo@sandia.gov</a>> writes:<br>
<br>
> Jed,<br>
><br>
> For the proposal, Heeho wants to demonstrate that a (well?) tuned black box preconditioner does not perform well (e.g. ILU[k], ILU[dt]). Ultimately, he plans to build on work by Qang Bui (currently a post-doc at LLNL), which is aligned with what you propose below, e.g.<br>
><br>
> Bui, Quan & Wang, Lu & Osei-Kuffuor, Daniel. (2018). Algebraic Multigrid Preconditioners for Two-phase Flow in Porous Media with Phase Transitions. Advances in Water Resources. 114. 10.1016/j.advwatres.2018.01.027.<br>
> Bui, Quan & C. Elman, Howard & Moulton, J. (2016). Algebraic Multigrid Preconditioners for Multiphase Flow in Porous Media. SIAM Journal on Scientific Computing. 39. 10.1137/16M1082652.<br>
><br>
> So, at this point, Heeho is looking for the best out-of-the-box preconditioners to demonstrate their poor performance. Or perhaps he should just employ PETSc's ILU[k] and move on.... <br>
><br>
> Glenn<br>
><br>
>> -----Original Message-----<br>
>> From: Jed Brown <<a href="mailto:jed@jedbrown.org" target="_blank">jed@jedbrown.org</a>><br>
>> Sent: Tuesday, March 5, 2019 9:06 PM<br>
>> To: Park, Heeho <<a href="mailto:heepark@sandia.gov" target="_blank">heepark@sandia.gov</a>>; <a href="mailto:petsc-dev@mcs.anl.gov" target="_blank">petsc-dev@mcs.anl.gov</a><br>
>> Cc: Park, Heeho Daniel <<a href="mailto:hdpark2@illinois.edu" target="_blank">hdpark2@illinois.edu</a>>; Hammond, Glenn E<br>
>> <<a href="mailto:gehammo@sandia.gov" target="_blank">gehammo@sandia.gov</a>><br>
>> Subject: [EXTERNAL] Re: [petsc-dev] external preconditioner availablilty for<br>
>> PETSc<br>
>> <br>
>> From a research perspective, it doesn't make sense to view these<br>
>> preconditioners as black boxes. Your problem will likely have an elliptic<br>
>> component (which you might approach using a multilevel method such as<br>
>> PCGAMG, PCML, PCHYPRE, or PCBDDC, all of which can accept some<br>
>> problem-specific input information as well as tunable parameters) combined<br>
>> (perhaps using PCFIELDSPLIT) with a transport solver (perhaps one-level<br>
>> domain decomposition). The details of the splits will take some thought and<br>
>> you'll want to compare to monolithic (unsplit) 1-level domain decomposition<br>
>> methods with suitably chosen subdomains and/or geometric multigrid. One<br>
>> way to start would be to do a literature search and try to reproduce the<br>
>> results from some methods in the literature. After that, you'll have a<br>
>> baseline for comparison and probably get some ideas about composition.<br>
>> <br>
>> "Park, Heeho via petsc-dev" <<a href="mailto:petsc-dev@mcs.anl.gov" target="_blank">petsc-dev@mcs.anl.gov</a>> writes:<br>
>> <br>
>> > Hi PETSc developers,<br>
>> ><br>
>> > I’m writing my proposal for my dissertation research at UIUC that will study<br>
>> on effectiveness of preconditioners for anisothermal, multiphase porous<br>
>> media flow calculations in parallel using PFLOTRAN. I know the link below lists<br>
>> preconditioners but from your experience, which preconditioning packages<br>
>> provide reliable and efficient PILUT, AMG, SA-AMG preconditioners for<br>
>> PETSc and do you have other preconditioner recommendations?<br>
>> > I used hypre PILUT, but the performance and the linear iteration count to<br>
>> solve a matrix is worse than ILU(0) which is not what I expected.<br>
>> ><br>
>> > <a href="https://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html" rel="noreferrer" target="_blank">https://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html</a><br>
>> ><br>
>> > Heeho Daniel Park<br>
>> ><br>
>> > ! ------------------------------------ !<br>
>> > Sandia National Laboratories<br>
>> > Org: 08844, R&D<br>
>> > Work: 505-844-1319<br>
>> > ! ------------------------------------ !<br>
<br>
<br>
<br>
<br>
</blockquote></div>