On Sat, Jan 29, 2011 at 4:26 AM, Stephen Wornom <span dir="ltr"><<a href="mailto:stephen.wornom@inria.fr">stephen.wornom@inria.fr</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Geometry: Tube with L/D is >> 1<br>
Characteristics:<br>
-Unstructured partitioned mesh with 500K vertices globally.<br>
-The tube wall is heated, thus solution evolves in the x-direction.<br>
-X is the dominant flow direction.<br>
-Seek steady solution using the time advancing scheme with a low Mach number preconditionner.<br>
*Question*: Which *PETSC* solver would give the best convergence? Stephen<br>
p.s.<br></blockquote><div><br></div><div>What are you currently using? I see two main points</div><div><br></div><div> a) Make sure your mesh partitioning is compatible with this dominant flow direction. It sounds like</div>
<div> any decent partition should be, but check it.</div><div><br></div><div> b) Probably more important is a good preconditioner for heat transfer coupled to incompressible flow. Have</div><div> you tried block preconditioning using FieldSplit. Treating the whole thing as a black box is usually</div>
<div> pretty terrible. An optimal preconditioner is described in the 4th talk by Marc Spiegelman here: <a href="http://www.bu.edu/pasi/materials/">http://www.bu.edu/pasi/materials/</a></div><div><br></div><div> Matt</div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
My present solver does not take into consideration that the flow has a dominant flow direction (x).<br>
Thus the convergence is very slow, 30000 time steps using 64-processors with a CFLmax= 50 applied in each cell. At 15000 time steps the 0-L/2 portion of the tube is converged with an additional 15000 time steps needed to converge the L/2-L part of the tube.<br>
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</font></blockquote></div><br><br clear="all"><br>-- <br>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener<br>