# Free Surface Calculation

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 June 6, 2008, 01:34 Free Surface Calculation #1 Casey Guest   Posts: n/a In my simulation, I have gas being injected tangentially into a cylinder full of water and I want to observe the free surface after steady state is reached. I've used the "Free Surface" option in Pro-am, but the calculation either stops due to divergence or the end result doesn't look what I expect for steady state. Any suggestions on which settings to change to improve the Free Surface function? Thanks in advance.

 June 7, 2008, 05:59 Re: Free Surface Calculation #2 murash-v Guest   Posts: n/a It must be transient. Example like you (1636KB): http://www3.msiu.ru/~murash-v/widsh.avi

 June 7, 2008, 07:05 Re: Free Surface Calculation #3 post-treatment question Guest   Posts: n/a Is the initial volume of gas conserved in this example? It does not seem to be. This happens in comet as well, there is a loss. Have you done a graph plot total mass of gas versus time?

 June 7, 2008, 07:28 Re: Free Surface Calculation #4 murash-v Guest   Posts: n/a volume or mass? I have compressible gas

 June 8, 2008, 01:47 Re: Free Surface Calculation #5 Casey Guest   Posts: n/a The volume of gas isn't conserved. I realized that I made a mistake in my original description. The cylinder is not completely full of water, but mostly (maybe 80%). There is an outlet that the two phase mixture can leave through.

 June 8, 2008, 11:17 Re: Free Surface Calculation #6 Pauli Guest   Posts: n/a Grid refinement & time step.

 June 8, 2008, 13:21 Re: Free Surface Calculation #7 Andrea Guest   Posts: n/a try also to use an UD scheme for the sim...you can restart later with a MARS scheme if you want to be correct with the results... And try also to initialize the sim via initfi.f, not by auto-initialization...if you can do that you'd probably get a more "stable" simulation

 June 13, 2008, 19:59 Re: Free Surface Calculation #8 Casey Guest   Posts: n/a Thanks everyone.