Dear Time, Thank you very much! I've been using the preconditioned CG solver that came with the tutorial thus far. I'll have a crack with GMRES.
Kind regards, Georgios On Sunday, August 19, 2018 at 1:23:29 AM UTC+1, Timo Heister wrote: > > Georgios, > > this is discussed very briefly in step-56: > If you use an iterative solver like GMRES, you can solve systems with > a 1 dimensional nullspace without problems. So what we do is that we > just ignore that the pressure is not uniquely defined. If you want to > ensure that your pressure has mean zero, you can do so after the fact > as it is done in step-56. I assume this is the same for 46 and 22. > Alternatively, you could fix one pressure DoF to 0 (we do this in > step-56 so that UMFPACK works for the problem). > > Best, > Timo > > On Fri, Aug 17, 2018 at 11:57 AM <[email protected] <javascript:>> > wrote: > > > > Dear all, > > > > In step 46 (and step 22 too if possible) for stokes, how to we ensure > that the pressure is uniquely defined (i.e. that it is in L^2_0)? > > > > Kind regards, > > Georgios > > > > -- > > The deal.II project is located at > https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dealii.org_&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=bcIbcHElg1BGpLoA0M-tnKwLnDNHIcibLzDgJkMhwaE&s=VUIbItbKS23blT7ZU4GysP2lqkxgXsCbl0RW9nE60aY&e= > > For mailing list/forum options, see > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_forum_dealii-3Fhl-3Den&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=bcIbcHElg1BGpLoA0M-tnKwLnDNHIcibLzDgJkMhwaE&s=m8j4Ssra1gjdzNXPFfhJdqlEfqOfWwZghy7xbZzNl4M&e= > > --- > > You received this message because you are subscribed to the Google > Groups "deal.II User Group" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected] <javascript:>. > > For more options, visit > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=bcIbcHElg1BGpLoA0M-tnKwLnDNHIcibLzDgJkMhwaE&s=7N-i5PNeYieD4LtOPMSjoPoA625VXXlDgVY33XVClks&e= > . > > -- > Timo Heister > http://www.math.clemson.edu/~heister/ > > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
