How to apply VOF method?

yeeking86 · March 19, 2009, 02:31

I am currently working on a model where there are microchannels on the surface with ANSYS CFX. Fluid will be passing through the surface without entering into the microchannels. My question is how do I apply VOF method in this problem? And what exactly is VOF method? I searched from the web but I found only theory, nothing much related to CFX.

Many many thanks to everyone.

mvoss · March 19, 2009, 03:58

hi.
tried to search the CFX help for VOF??
i think there will be hit.

neewbie

yeeking86 · March 19, 2009, 05:40

I tried to search but could hardly find any useful information. Is there any tutorial which show VOF method step by step?

Thank you

mvoss · March 19, 2009, 05:56

hi,

i guess
Tutorial 7: Free Surface Flow Over a Bump
Tutorial 15: Multiphase Flow in Mixing Vessel

yeeking86 · March 19, 2009, 08:02

I will try the tutorial. But can anyone briefly tell me how to apply VOF in a flowing fluid?
Thank you.

mvoss · March 19, 2009, 09:00

hi,

What do you mean by VOF?
I suppose it is Volume Of Fluid.... which means "everthing is multiplied by the volume fraction of the specific fluid (water, oil, air, ...)and summed up over the cellvolume".
If you turn on multiple fluids, CFX generates the necessary values for each component by multiplying the value with the additional transport equation for the volume fraction of that fluid in each cell.
Specify the mass transfer -rate if necessary and the interacting between each pair of phases.

neewbie

helly · August 23, 2010, 11:28

hi
I am working with ansys flotran now and have a problem.
i had analyzed a model some years ago using ansys 7 and VOF method, a problem about cavitation. now i am simulating that problem again with ansys 12 (flotran)
but that dose not run? the error says: "flotran VOF cant be run now and you should turn off parallel processing" or somthing like that. i dont know what parallel processing is! but i am sure that the software is working correctly on my PC, i have run several problems which dont use VOF and everything is ok, but using VOF the error emerges.
i need to run the model again but i cant. i have checked all the steps of applying BCs using ansys manual, VOF section, but still there is the error! can anybody help me please?

ghorrocks · August 23, 2010, 18:24

Flotran is a long dead and buried solver. Time to move to a modern solver. And this forum is for CFX so you won't get much help with other solvers.

March 19, 2009, 02:31	How to apply VOF method?	#1
yeeking86 New Member King Join Date: Mar 2009 Posts: 8 Rep Power: 17	I am currently working on a model where there are microchannels on the surface with ANSYS CFX. Fluid will be passing through the surface without entering into the microchannels. My question is how do I apply VOF method in this problem? And what exactly is VOF method? I searched from the web but I found only theory, nothing much related to CFX. Many many thanks to everyone.

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March 19, 2009, 03:58		#2
mvoss Senior Member Matthias Voß Join Date: Mar 2009 Location: Berlin, Germany Posts: 449 Rep Power: 20	hi. tried to search the CFX help for VOF?? i think there will be hit. neewbie

March 19, 2009, 05:40		#3
yeeking86 New Member King Join Date: Mar 2009 Posts: 8 Rep Power: 17	I tried to search but could hardly find any useful information. Is there any tutorial which show VOF method step by step? Thank you

March 19, 2009, 05:56		#4
mvoss Senior Member Matthias Voß Join Date: Mar 2009 Location: Berlin, Germany Posts: 449 Rep Power: 20	hi, i guess Tutorial 7: Free Surface Flow Over a Bump Tutorial 15: Multiphase Flow in Mixing Vessel

March 19, 2009, 08:02		#5
yeeking86 New Member King Join Date: Mar 2009 Posts: 8 Rep Power: 17	I will try the tutorial. But can anyone briefly tell me how to apply VOF in a flowing fluid? Thank you.

March 19, 2009, 09:00		#6
mvoss Senior Member Matthias Voß Join Date: Mar 2009 Location: Berlin, Germany Posts: 449 Rep Power: 20	hi, What do you mean by VOF? I suppose it is Volume Of Fluid.... which means "everthing is multiplied by the volume fraction of the specific fluid (water, oil, air, ...)and summed up over the cellvolume". If you turn on multiple fluids, CFX generates the necessary values for each component by multiplying the value with the additional transport equation for the volume fraction of that fluid in each cell. Specify the mass transfer -rate if necessary and the interacting between each pair of phases. neewbie

August 23, 2010, 11:28		#7
helly New Member helle Join Date: Aug 2010 Posts: 6 Rep Power: 15	hi I am working with ansys flotran now and have a problem. i had analyzed a model some years ago using ansys 7 and VOF method, a problem about cavitation. now i am simulating that problem again with ansys 12 (flotran) but that dose not run? the error says: "flotran VOF cant be run now and you should turn off parallel processing" or somthing like that. i dont know what parallel processing is! but i am sure that the software is working correctly on my PC, i have run several problems which dont use VOF and everything is ok, but using VOF the error emerges. i need to run the model again but i cant. i have checked all the steps of applying BCs using ansys manual, VOF section, but still there is the error! can anybody help me please?

August 23, 2010, 18:24		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Flotran is a long dead and buried solver. Time to move to a modern solver. And this forum is for CFX so you won't get much help with other solvers.