Hi Tay, I've just been working on ways to get more accurate pressure from the Poisson equation. I can highly recommend this article by Guermond and coworkers:
http://dx.doi.org/10.1016/j.cma.2005.10.010 It's so long that it may be scary, but just reading 3.1 and 3.2 gives quite a bit of information already. The article sums up the literature quite nicely. Regards, Åsmund Ervik > Date: Thu, 21 Nov 2013 18:06:11 +0800 > From: TAY wee-beng <[email protected]> > To: Jed Brown <[email protected]>, PETSc list > <[email protected]> > Subject: Re: [petsc-users] Modify RHS values at each iteration > Message-ID: <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Hi Jed, > > I need a solve a Poisson equation, which is part of my finite volume CFD > code. > > The RHS terms are calculated from the velocity. > > In the standard mtd, the RHS terms are calculated from the velocity, > which then solves the Poisson eqn to get the pressure. > > Now, to improve the accuracy of the pressure obtained, a paper suggested > obtaining the pressure from the velocity in 1 iteration. Then use the > new pressure for the momentum eqn to get a more accurate intermediate > velocity. The RHS terms are recomputed again using the new velocity, > which is then used to calculate the new pressure. This cycle goes on > until the pressure converges to a certain value. > > Hence, I wonder what is the best way to do it. > > Thanks! > > Yours sincerely, > > TAY wee-beng > > On 21/11/2013 3:44 PM, Jed Brown wrote: >> TAY wee-beng <[email protected]> writes: >>> Hi, in that case, do you want any suggestion? Is it possible to apply >>> the preconditioner only once at the start, and not at every intermediate >>> step? >> You'll have to explain what you are trying to do. >
