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-   -   Another question on Free Surface (http://www.cfd-online.com/Forums/cfx/19652-another-question-free-surface.html)

Miko May 26, 2003 21:30

Another question on Free Surface
 
Now I have another question. For free surface flow in vacuum, how can I simulate it?

Robin May 27, 2003 16:42

Re: Another question on Free Surface
 
Hi Miko,

This is not physically realistic. To have a liquid free surface, there must be some gas phase applying pressure.

If you like, you can specify your second phase to have a very small density, but I suspect you will have problems if it is too small.

Robin

Miko May 27, 2003 21:13

Re: Another question on Free Surface
 
Hi Robin,

Yes, you are right. I think I should apply a certain gas around it. If the density of the gas is small but with certain value of pressure, is it possible?

Robin May 28, 2003 09:53

Re: Another question on Free Surface
 
Yes, but if the density of your gas is too low, you may experience convergence problems.

Robin

Miko May 28, 2003 20:31

Re: Another question on Free Surface
 
Hi Robin,

Oh, I see. OK, I will pay attention it. Thank you!

Best regards!

Miko

Peter Bartsch May 30, 2003 05:06

Re: Another question on Free Surface
 
I recommend that you calculate Knudsen number (mean free path / reactor dimension) for the gas side. It should be <0.1 otherwise the continuum assumption inherent to CFD codes is no longer valid.

Peter


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