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IDProjectCategoryView StatusDate SubmittedLast Update
0002322OpenFOAMContributionpublic2016-11-08 10:402017-06-30 12:22
Reporterbjnieuwboer Assigned Tochris  
PrioritynormalSeverityfeatureReproducibilityhave not tried
Status closedResolutionfixed 
PlatformGNU/LinuxOSUbuntuOS Version14.10
Summary0002322: feature/bug: New powerlaw velocity boundary condition based on wall or patch distance
DescriptionMy request is two-sided but connected
1) I would like to submit a powerlaw velocity boundary condition for inlet patches. This powerlaw velocity profile will need a shorter adjustment time/length for creating a fully turbulent profile. It is based on the chalmers implementation of it (http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2009/JanPotac/reportPotac.pdf). It computes the distance to the nearest wall (or patch if patchActAsWall is set to true and a patch is specified). Based upon the distance to the wall per face and a maximum distance, the profile is computed. The code can be found in powerLawVelocity.tar.gz. Now the distance to the wall is given as output. Is it possible to implement this boundary condation, when issue 2 is solved?

2) The boundary condition does not work correctly since the distance to a wall or patch is not correctly computed on a wall or patch. In mesh.png you see the mesh with an patch inlet defined by the two black lines. On the left side the mesh is finer than on the right side. In inletPatchDistance.png you see the nearwall distances on the patch (it says velocities, but the boundary condition now gives the wall distance as output). You can see that these are not symmetrical, which is caused by the fact that the wall distances are taken into account for the cell-centers and then copied to the faces and walls. This behaviour is the same for wall/and patch distances. Is it possible to do a computation of the wall distance for patches? Then the boundary condition would work correctly.
Steps To Reproduce1) Compile powerLawVelocity boundary condition
2) Run the powerLawInletTest case
3) see the inletvelocities at the jet (which repressent the wall/patch distance)
TagsNo tags attached.

Activities

bjnieuwboer

2016-11-08 10:40

reporter  

powerLawVelocity.tar.gz (93,799 bytes)

bjnieuwboer

2016-11-08 10:41

reporter  

powerLawInletTest.tar.gz (88,345 bytes)

bjnieuwboer

2016-11-08 10:41

reporter  

inletPatchDistance.png (12,667 bytes)   
inletPatchDistance.png (12,667 bytes)   

bjnieuwboer

2016-11-08 10:41

reporter  

Mesh.png (17,361 bytes)   
Mesh.png (17,361 bytes)   

chris

2017-06-30 12:22

manager   ~0008302

This contribution includes the simpler elements of writing the boundary condition without addressing the more complex issue of specifying distance to wall on a patch. It does not use wallDist::New for example. It is also too specific, e.g. it would be possible to write a more general boundary condition that uses Function1 for the profile, allowing the user to specify a wider variety of functions. A power law would need to be added to Function1.

Issue History

Date Modified Username Field Change
2016-11-08 10:40 bjnieuwboer New Issue
2016-11-08 10:40 bjnieuwboer File Added: powerLawVelocity.tar.gz
2016-11-08 10:41 bjnieuwboer File Added: powerLawInletTest.tar.gz
2016-11-08 10:41 bjnieuwboer File Added: inletPatchDistance.png
2016-11-08 10:41 bjnieuwboer File Added: Mesh.png
2017-06-30 12:22 chris Assigned To => chris
2017-06-30 12:22 chris Status new => closed
2017-06-30 12:22 chris Resolution open => fixed
2017-06-30 12:22 chris Note Added: 0008302