subcritical water flow with a waterfall at the outlet

Ema40 · April 21, 2015, 07:17

Hi everybody.

I am simulating an open channel flow, subcritical flow. At the outlet the flow has an atmospheric pressure, since it ends with a waterfall in a tank (the tank has not been simulated, so the outlet is where the channel ends). Have I to specify the gauge pressure=atmospheric pressure and stop, or also the water depth?

Thanks
By

why? · April 23, 2015, 22:00

What do you mean? I suppose if it is atmospheric pressure it should stay 0 Pa gauge pressure at the outlet.

Actually the difference in the pressures of the inlet and outlet should be what you expect the pressure fall/rise to be between the inlet and outlet just to give good starting point to the solver.

So the result with pressure at inlet 40 Pa and outlet 0, and another simulation result with inlet 80 Pa and outlet 40 Pa, will I think be the same.

That is what I think, cant guarantee if what I am saying is right.

Ema40 · April 24, 2015, 16:41

Hi.
Thank you for your response!

April 21, 2015, 07:17	subcritical water flow with a waterfall at the outlet	#1
Ema40 Senior Member Join Date: Oct 2014 Posts: 124 Rep Power: 12	Hi everybody. I am simulating an open channel flow, subcritical flow. At the outlet the flow has an atmospheric pressure, since it ends with a waterfall in a tank (the tank has not been simulated, so the outlet is where the channel ends). Have I to specify the gauge pressure=atmospheric pressure and stop, or also the water depth? Thanks By

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April 23, 2015, 22:00		#2
why? New Member Join Date: Apr 2015 Posts: 16 Rep Power: 11	What do you mean? I suppose if it is atmospheric pressure it should stay 0 Pa gauge pressure at the outlet. Actually the difference in the pressures of the inlet and outlet should be what you expect the pressure fall/rise to be between the inlet and outlet just to give good starting point to the solver. So the result with pressure at inlet 40 Pa and outlet 0, and another simulation result with inlet 80 Pa and outlet 40 Pa, will I think be the same. That is what I think, cant guarantee if what I am saying is right.

April 24, 2015, 16:41		#3
Ema40 Senior Member Join Date: Oct 2014 Posts: 124 Rep Power: 12	Hi. Thank you for your response!