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-   -   gas/liquid outlet in circulating zone (http://www.cfd-online.com/Forums/fluent/27448-gas-liquid-outlet-circulating-zone.html)

 Paal Chr. January 18, 2000 04:03

gas/liquid outlet in circulating zone

Hi there,

I'm working with a gas/liquid, stirred tank reactor. I have given up using a free surface in the system, so I have to put the outlet close to where the surface is expected to be, but in the two-phase area. My problem is then how twp specify the outlet parameters. My guess is that I have to skip the outlet and use a sink term for the gas fraction instead. Does anyone have a better idea?

How can I link the gas fraction at the inlet to this sink term so I will be guarantied that the conservation equation will be fullfilled?

I hope someone can help me.

PC.

 S. Vasquez January 21, 2000 16:01

Re: gas/liquid outlet in circulating zone

HI,

You can probably do this problem as follows:

i) Use Adjust UDS and calculate the total mass of gas going into the system. ii) You can use symmetry (or link-cut walls) b.c for the liquid in the "modified outlet"

ii) Use this total gas in to adjust the velocities of the gas at the cells near the "special outlet". This can be done via urstrm.F (user defined subroutine for source terms in the equations) by setting a sink term for the velocities on that region. You may also be able to do via "adjust UDS."

iii) Use the urstrm.F subroutine to set a sink term for the volume of fraction equations.

iv) Contact your support engineer for more specific questions about variables in the UDS files.

v) Depending of the gas inlet velocity you may also be able to do this problem with Fluent5 (UNS)

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