View Issue Details Jump to Notes ] Issue History ] Print ]
IDProjectCategoryView StatusDate SubmittedLast Update
0000134OpenFOAM[All Projects] Bugpublic2011-02-10 12:422012-11-05 14:29
Reporterbgschaid 
Assigned To 
PrioritynormalSeveritymajorReproducibilityhave not tried
StatusclosedResolutionno change required 
PlatformOSOS Version
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)
TagsNo tags attached.
Attached Files

- Relationships

-  Notes
(0000238)
henry (manager)
2011-02-10 12:50

Using

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.
(0000239)
bgschaid (reporter)
2011-02-10 17:35

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 andy Status new => closed
2011-03-17 15:47 andy Resolution open => no change required