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Old   May 21, 2008, 22:09
Default Help with slug flow simulation.
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Kes
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Dear all, i was previously trying to model droplet formation with a slug flow pattern in a T-junction and it was working fine. When i increase the flow rate of the oil phase (i'm creating water in oil emulsion), the droplets decrease in size which is expected. However the droplets are sticking to the walls and are not located at the centre of the tube even when it is smaller than the diameter of the tube. Thus i think this is due to me turning on the Wall Adhesion option under Define->Phases->Interaction. I turned it off and now i couldn't get back the flow pattern that i wanted. The solutions take very long to converge when i am using the time step recommended by the Fluent system, around 30-40 iterations per time step and the flow pattern that results is somewhat like the slug flow disintegrating into small bubbles. Reversed flow is also observed during iterations. Therefore i would like to ask if anybody could guide me the right way?
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Old   May 26, 2008, 13:58
Default Re: Help with slug flow simulation.
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Renato Pacheco
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are you following any flow pattern map?? because normally when you change the flow rate or the velocities, probably you will get another flow pattern. so you should follow this maps to see witch pattern you should get. I suggest the baker chart, as long as he has some corrections for fluids different from air or water, and as i see you are using oil.

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Old   May 27, 2008, 04:48
Default Re: Help with slug flow simulation.
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Kes
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Ok but i have checked the baker chart and the result i'm trying to get is something between plug flow and slug flow. However in the Fluent documentation help it has classified all of these into slug flow, therefore i used the VOF model.

Recently i tried the simulation again without Wall Adhesion and with a smaller time step, resulting in a more coherent result. However this one has the droplet formed clinging onto the wall and with a tail that extends from it all the way to the water phase inlet, which is not what i wanted.

Please advice.
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