2016-10-01 02:44 BST

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IDProjectCategoryView StatusLast Update
0000134OpenFOAM[All Projects] Bugpublic2012-11-05 14:29
Assigned To 
PrioritynormalSeveritymajorReproducibilityhave not tried
StatusclosedResolutionno change required 
Product Version 
Target VersionFixed in Version 
Summary0000134: Unphysical velocity patterns at the interface of a porous zone
DescriptionAs described in http://www.cfd-online.com/Forums/openfoam/82729-poroussimplefoam-oscillating-velocity-porous-zone.html for low permeabilities there is an oscillation at the interface of a porous zone. Investigations show that after the pressure correction phi is correct but the ripples are introduced by U -= rUA*fvc::grad(p) (equivalent formulation for the incompressible solvers) possibly by the differences in the matrix. This can be avoided by doing the complete reconstruction U = fvc::reconstruct(phi) (divide by rho for compressible solvers)
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henry (manager)


U = fvc::reconstruct(phi);

causes a HUGE momentum conservation error but if momentum conservation is not important in your cases then yes it does remove spurious "wiggles" of many kinds.


bgschaid (reporter)

Point taken. Should have checked that too (pressure drop and velocity profiles were alright)

Anyway: for models that use U these wiggles produce "interesting" results. For instant when taking the angledDuctImplicit/rhoPorousSimpleFoam-tutorial and increasing the Darcy coefficient by two orders of magnitude one sees that each porous interface "produces" turbulence. Probably because the kEpsilon-model takes the gradient of the wiggle. Other stuff (lagrangian) might be affected, too

So it is not a purly cosmetic/postprocessing problem

-Issue History
Date Modified Username Field Change
2011-02-10 12:42 bgschaid New Issue
2011-02-10 12:50 henry Note Added: 0000238
2011-02-10 17:35 bgschaid Note Added: 0000239
2011-03-17 15:47 user2 Status new => closed
2011-03-17 15:47 user2 Resolution open => no change required
+Issue History