CrankNicholson returns wrong dimensions and sound speed when mesh is moving

lillberg · February 23, 2009, 08:42

Hi,

I've found that the fvc::ddtPhiCorr(rUA, rho, U, phi) function returns wrong dimensions for CrankNicholson when the mesh is moving.

Also, the sound speed is approx. half the physical value for an planar acoustic wave when the mesh is moving and CN is used. Has nothing to do with ddtPhiCorr.

Looking at the source it seems that the handling of moving meshes is quite different from e.g. backward.

All other time schemes works Ok.

If mesh.update() is removed from the application code everything works fine.

Best regards

/Eric

henry · February 23, 2009, 09:40

Which version of OpenFOAM are you running and which solver?

H

lillberg · February 23, 2009, 11:44

Sorry, not used to posting bugs ;-)

Latest git version

Home made solver for FSI using the couple manager

/Eric

lillberg · February 23, 2009, 11:47

I didn't get the code truough but I'm pretty sure you could reproduce the problem by introducing a dynamicFvMesh and a mesh.update() in for example the coodles code.

/Eric

lillberg · February 23, 2009, 13:53

Yepp, changing your ordinary coodles code by adding a dynamicFvMesh and doing mesh.update() at the same time as using CN timeScheme reproduces the bug.

I ran it on a simple 2D channel with slip walls, waveTransmissive outlet, an oscillating inlet velocity at 100 Hz and air as medium. The fvcDdtPhiCorr returns wrong dimensions, and if it's commented out the soundspeed is reduced to half its physical value.

/Eric

lillberg · April 29, 2009, 05:24

Hi Henry,

Any news on this bug?

/Eric

henry · May 4, 2009, 17:53

Eric,

I haven't forgotten, it is still on my list of things to do and I will deal with it shortly.

H

February 23, 2009, 08:42	Hi, I've found that the fvc	#1
lillberg Member Eric Lillberg Join Date: Mar 2009 Location: Stockholm Posts: 80 Rep Power: 17	Hi, I've found that the fvc::ddtPhiCorr(rUA, rho, U, phi) function returns wrong dimensions for CrankNicholson when the mesh is moving. Also, the sound speed is approx. half the physical value for an planar acoustic wave when the mesh is moving and CN is used. Has nothing to do with ddtPhiCorr. Looking at the source it seems that the handling of moving meshes is quite different from e.g. backward. All other time schemes works Ok. If mesh.update() is removed from the application code everything works fine. Best regards /Eric

February 23, 2009, 09:40	Which version of OpenFOAM are	#2
henry Senior Member Join Date: Mar 2009 Posts: 854 Rep Power: 22	Which version of OpenFOAM are you running and which solver? H

February 23, 2009, 11:44	Sorry, not used to posting bug	#3
lillberg Member Eric Lillberg Join Date: Mar 2009 Location: Stockholm Posts: 80 Rep Power: 17	Sorry, not used to posting bugs ;-) Latest git version Home made solver for FSI using the couple manager /Eric

February 23, 2009, 11:47	I didn't get the code truough	#4
lillberg Member Eric Lillberg Join Date: Mar 2009 Location: Stockholm Posts: 80 Rep Power: 17	I didn't get the code truough but I'm pretty sure you could reproduce the problem by introducing a dynamicFvMesh and a mesh.update() in for example the coodles code. /Eric

February 23, 2009, 13:53	Yepp, changing your ordinary c	#5
lillberg Member Eric Lillberg Join Date: Mar 2009 Location: Stockholm Posts: 80 Rep Power: 17	Yepp, changing your ordinary coodles code by adding a dynamicFvMesh and doing mesh.update() at the same time as using CN timeScheme reproduces the bug. I ran it on a simple 2D channel with slip walls, waveTransmissive outlet, an oscillating inlet velocity at 100 Hz and air as medium. The fvcDdtPhiCorr returns wrong dimensions, and if it's commented out the soundspeed is reduced to half its physical value. /Eric

April 29, 2009, 05:24		#6
lillberg Member Eric Lillberg Join Date: Mar 2009 Location: Stockholm Posts: 80 Rep Power: 17	Hi Henry, Any news on this bug? /Eric

May 4, 2009, 17:53		#7
henry Senior Member Join Date: Mar 2009 Posts: 854 Rep Power: 22	Eric, I haven't forgotten, it is still on my list of things to do and I will deal with it shortly. H

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