Free surface is not falling (VOF MODEL, TANK DRAINAGE)
 

https://www.dropbox.com/s/kqoz0ktxkt98k7e/fpic.jpg
Hi,
I am modeling a tank drainage on VOF model of Fluent. Tank has a simple rectangular shape having one inlet at the top and three outlets at bottom. Tank's lower volume is filled with water (using adapt region) and upper volume by air.

Simulation Parameters:
Inlet: Velocity inlet
Outlets: Pressure outlet
Incoming Fluid through inlet is water.
Explicit scheme, CFL=2.0, Geo-reconstruct, Variable Time iteration

Inlet area is large than the sum of three outlets.

My problem:
(a) When I put X m/s velocity at inlet BC, all three outlets shows about same outlet velocity. Is it correct?

(b) There is no change in free surface level of water in the tank. I have checked REPORT FLUXES of inlet and all outlets, inlet flux=outlets fluxes.
why free surface is not falling or rising? I have changed inlet velocity but there is no change in free surface and incoming & out going fluxes remains constant. In practical phenomenon free surface should fall.

Image attached

Please help me.

Thanks

Please any one reply

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Same problem
 

Hi,
I am trying to simulate water draining from at a tank at 10 meter elevation through a pipe. I am using ANSYS FLUENT to do that. I am using VOF for modelling.
I am having difficulties in defining the inlet and outlet boundary condition.
Right now, I am using pressure-inlet and pressure-outlet for inlet and outlet boundary conditions, but after running the code, it shows a lot of secondary flow within the tank and pipe.
anyone have an idea about that?