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IDProjectCategoryView StatusDate SubmittedLast Update
0000654OpenFOAMBugpublic2012-10-03 16:352012-12-04 18:05
Reporteruser521Assigned Touser2 
PrioritynormalSeveritymajorReproducibilityalways
Status resolvedResolutionfixed 
PlatformCore2 Duo CPU T7100 @ 1.8Hz x 2OSUbuntuOS VersionUbuntu 12.04 64
Summary0000654: The pressure value is not correctly determined in potentialFreeSurfaceFoam
Description
I ran the tutorial example oscillatingBox of potentialFreeSurfaceFoam. The values of the forces on the floatingObject in the y direction were negative (there is suction acting on the box). I plotted the pressure along a vertical line crossing the domain using paraView. At the free surface the pressure is zero, as it should be, but just beneath the free surface the pressure has a huge jump to negative, decreasing in absolute value as the distance to surface increases. The jump in pressure to negative is equivalent to the hydrostatic pressure that should be found at the bottom
Steps To ReproduceRun the potentialFreeSurface tutorial called oscillatingBox in OpenFoam 2.1.x without any modification.
Additional InformationThe value of the pressure jump being equal to the what the hydrostatic pressure should be at the bottom of the domain seems to indicate that there is a referencing problem for the total pressure. In the file createFields.H at lines 79 and 80 the following code determining the reference level is found

 " refLevel.boundaryField()[freeSurfacePatchI]
        == mesh.C().boundaryField()[freeSurfacePatchI];"

Two things about this:

First, I think that the " == " operator should be " = ". Second, this referencing only considers the free surface. Indeed, at the free surface the pressure is correct. Some definitions of the reference value for the other boundaries and interior domain are needed.
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Activities

user521

2012-10-03 16:35

 

kinematicPressure.png (14,217 bytes)   
kinematicPressure.png (14,217 bytes)   

user2

2012-12-04 18:05

  ~0001812

Thanks for the report - fixed by commit 015ce1e

Issue History

Date Modified Username Field Change
2012-10-03 16:35 user521 New Issue
2012-10-03 16:35 user521 File Added: kinematicPressure.png
2012-12-04 18:05 user2 Note Added: 0001812
2012-12-04 18:05 user2 Status new => resolved
2012-12-04 18:05 user2 Fixed in Version => 2.1.x
2012-12-04 18:05 user2 Resolution open => fixed
2012-12-04 18:05 user2 Assigned To => user2