Cavitation problem...

Roland R · September 15, 2011, 09:59

Hello,

I would like to simulate the next phenomenon:

There is a small cylinder which is loaded with water fully. (Cylinder is fully closed.) Volume of the cylinder starts to increase slowly until the start of the cavitation process. Finally the volume decreases back to the original value, the cavitation bubbles disappier, the water vapour turns into water and water phase will be in the full field again.

In the simulation this process operates until the beginning of cavitation, water wapour develops in the field, but this phase does not turn into water after decreasing of the volume.

Are there some ideas to solve this problem?

Thanks in advance;
Roland

singer1812 · September 15, 2011, 11:12

Make sure you use slightly compressible water.

Roland R · September 15, 2011, 11:22

Quote:

Originally Posted by singer1812

Make sure you use slightly compressible water.

The water is compressible in the simulation

singer1812 · September 15, 2011, 11:40

My apologies, I didnt read your thread thoroughly enough. I thought you were asking about general modeling, didnt see that you were asking about condensation of the vapour phase.

Are you using the your cavitation model or what? Did you verify that the pressure in the vapour regions is heading above the vapour pressure?

Are you sure it is not turning into water? Are you monitoring the total amount of vapour in the volume as a function of time? If it is decreasing, perhaps you just havent run the simulation long enough.

September 15, 2011, 09:59	Cavitation problem...	#1
Roland R Senior Member Roland Rakos Join Date: Mar 2009 Posts: 131 Rep Power: 17	Hello, I would like to simulate the next phenomenon: There is a small cylinder which is loaded with water fully. (Cylinder is fully closed.) Volume of the cylinder starts to increase slowly until the start of the cavitation process. Finally the volume decreases back to the original value, the cavitation bubbles disappier, the water vapour turns into water and water phase will be in the full field again. In the simulation this process operates until the beginning of cavitation, water wapour develops in the field, but this phase does not turn into water after decreasing of the volume. Are there some ideas to solve this problem? Thanks in advance; Roland

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September 15, 2011, 11:12		#2
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 21	Make sure you use slightly compressible water.

September 15, 2011, 11:40		#4
singer1812 Senior Member Edmund Singer P.E. Join Date: Aug 2010 Location: Minneapolis, MN Posts: 511 Rep Power: 21	My apologies, I didnt read your thread thoroughly enough. I thought you were asking about general modeling, didnt see that you were asking about condensation of the vapour phase. Are you using the your cavitation model or what? Did you verify that the pressure in the vapour regions is heading above the vapour pressure? Are you sure it is not turning into water? Are you monitoring the total amount of vapour in the volume as a function of time? If it is decreasing, perhaps you just havent run the simulation long enough.