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Rupp Carriveau July 6, 2001 11:26

Tracking Flow Issuing From Outlet
I have a simple gravity driven funnel flow. This is not unlike filling a funnel at your kitchen sink and just letting it drain out. I would like to know how I would go about getting the details of the flow issuing from the outlet of the funnel. Mostly I am interested in the flow profile, i.e., is it possible to quantify the vena contracta exiting that boundary? Or, do I have to mesh the region where I suspect the vena contracta will occur? If this is so, how would one set-up the BC's? I mean, I have a free surface at the top, no problem, but then how do you bound the free surface exit when there is yet mesh downstream of that point?

I hope my question is somewhat clear.

Thanks to all who have helped me thus far!


John C. Chien July 7, 2001 05:28

Re: Tracking Flow Issuing From Outlet
(1). The problem itself is very simple. (2). you will have transient flow with free surface at the top at the atmospheric pressure, and the liquid jet will also subject to the same pressure and the gravitational field. (3). Whether the code can handle it or not, you should try to get the answer from the code vendor. If they have a sample case for this, then I guess it can be done. (4). Otherwise, you will have to write the code to solve it. And because of the gravitational field, the liquid jet will move faster in the downward direction, by continuity, the diameter of the jet will get smaller. Then the surface wave instability will set in, the jet will break up into spray.

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