Another question on Free Surface

May 26, 2003, 21:30

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

May 27, 2003, 16:42

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

May 27, 2003, 21:13

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?

May 28, 2003, 09:53

Yes, but if the density of your gas is too low, you may experience convergence problems.

Robin

May 28, 2003, 20:31

Hi Robin,

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

Best regards!

Miko

May 30, 2003, 05:06

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0.1 otherwise the continuum assumption inherent to CFD codes is no longer valid.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

May 26, 2003, 21:30	Another question on Free Surface	#1
Miko Guest Posts: n/a	Now I have another question. For free surface flow in vacuum, how can I simulate it?

May 27, 2003, 16:42	Re: Another question on Free Surface	#2
Robin Guest Posts: n/a	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

May 27, 2003, 21:13	Re: Another question on Free Surface	#3
Miko Guest Posts: n/a	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?

May 28, 2003, 09:53	Re: Another question on Free Surface	#4
Robin Guest Posts: n/a	Yes, but if the density of your gas is too low, you may experience convergence problems. Robin

May 28, 2003, 20:31	Re: Another question on Free Surface	#5
Miko Guest Posts: n/a	Hi Robin, Oh, I see. OK, I will pay attention it. Thank you! Best regards! Miko

May 30, 2003, 05:06	Re: Another question on Free Surface	#6
Peter Bartsch Guest Posts: n/a	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0.1 otherwise the continuum assumption inherent to CFD codes is no longer valid.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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