reservoir feed into a channel

aerospace_guy_ · January 27, 2012, 10:34

Hi All,

What I am trying to model is using a stream of high speed-low pressure air to suck a liquid from a reservoir. At the moment, I have a venturi where air is sped up and the pressure is dropped to about half atmospheric, a reservoir with water is fed into the channel at the point where the pressure is lowest. What I am seeing is a small portion of water flowing into the channel, but not nearly what I would expect. I'm curious if my setup is correct since I am new to multiphase flow.

The air-inlet is an inlet boundary with normal velocity at 150m/s and air volume fraction at 1 with water fraction at 0, the outlet is an outlet boundary of zero relative average static pressure, and at the top of the reservoir, I have an opening at zero relative (atmospheric) pressure, but volume fraction of water at 1, and air at 0.

my setup includes buoyancy and turbulence with a free slip condition on all walls for air, and no-slip for the liquid as I recall was the case from the tutorial.

Does anyone know of a better way to model a reservoir than what I've done, or see any glaring mistakes in my model? let me know if you'd like me to post pictures.

Thanks

ghorrocks · January 29, 2012, 05:25

The big issue is what does the water do to enter the air stream? And how do you model it?

My guess is the high velocity air strips water from the surface and very quickly smashes it down to quite small droplets. This means I suspect you will need three phases to model this - one air phase, one continuous liquid phase and one dispersed liquid phase for the droplets. At the surface you will need to define a model which takes water from the continuous phase and creates droplets in the disperse phase.

January 27, 2012, 10:34	reservoir feed into a channel	#1
aerospace_guy_ New Member Steven Join Date: Feb 2011 Location: Calgary, Canada Posts: 13 Rep Power: 15	Hi All, What I am trying to model is using a stream of high speed-low pressure air to suck a liquid from a reservoir. At the moment, I have a venturi where air is sped up and the pressure is dropped to about half atmospheric, a reservoir with water is fed into the channel at the point where the pressure is lowest. What I am seeing is a small portion of water flowing into the channel, but not nearly what I would expect. I'm curious if my setup is correct since I am new to multiphase flow. The air-inlet is an inlet boundary with normal velocity at 150m/s and air volume fraction at 1 with water fraction at 0, the outlet is an outlet boundary of zero relative average static pressure, and at the top of the reservoir, I have an opening at zero relative (atmospheric) pressure, but volume fraction of water at 1, and air at 0. my setup includes buoyancy and turbulence with a free slip condition on all walls for air, and no-slip for the liquid as I recall was the case from the tutorial. Does anyone know of a better way to model a reservoir than what I've done, or see any glaring mistakes in my model? let me know if you'd like me to post pictures. Thanks

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January 29, 2012, 05:25		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	The big issue is what does the water do to enter the air stream? And how do you model it? My guess is the high velocity air strips water from the surface and very quickly smashes it down to quite small droplets. This means I suspect you will need three phases to model this - one air phase, one continuous liquid phase and one dispersed liquid phase for the droplets. At the surface you will need to define a model which takes water from the continuous phase and creates droplets in the disperse phase.