Outlet BC with Vof?

Januel · May 26, 2012, 05:24

Hello,

Question from a beginner:

I am running an analysis of a buoy with Vof and eulerian multiphase air/sea water. But what is the difference between the "Volum fraction air/sea water" and "Volume fraction Heavy/light fluid" boundary conditions? Manuals from CD-adapco suggest that "Heavy/light" fluid be used for velocity inlet and "air/sea water" for pressure outlet. When I use these settings it does not converge, but using "heavy/light" BC on outlet gives good convergence...

Running with 2DOF, z-translation and y-rotation (the latter rather large; <25 deg pitch-up).

Thanks!

Ladnam · May 28, 2012, 15:29

Heavy/light is the undisturbed volume fraction. Air/water is the resulting/disturbed volume fraction. So heavy/light should be used for BC.

Januel · May 28, 2012, 15:48

Thanks alot! Been wondering about that one and was unable to find an answer...

May 26, 2012, 05:24	Outlet BC with Vof?	#1
Januel New Member Join Date: Mar 2012 Posts: 2 Rep Power: 0	Hello, Question from a beginner: I am running an analysis of a buoy with Vof and eulerian multiphase air/sea water. But what is the difference between the "Volum fraction air/sea water" and "Volume fraction Heavy/light fluid" boundary conditions? Manuals from CD-adapco suggest that "Heavy/light" fluid be used for velocity inlet and "air/sea water" for pressure outlet. When I use these settings it does not converge, but using "heavy/light" BC on outlet gives good convergence... Running with 2DOF, z-translation and y-rotation (the latter rather large; <25 deg pitch-up). Thanks!

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May 28, 2012, 15:29		#2
Ladnam Member Join Date: May 2010 Posts: 37 Rep Power: 5	Heavy/light is the undisturbed volume fraction. Air/water is the resulting/disturbed volume fraction. So heavy/light should be used for BC.

May 28, 2012, 15:48		#3
Januel New Member Join Date: Mar 2012 Posts: 2 Rep Power: 0	Thanks alot! Been wondering about that one and was unable to find an answer...