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Unsteady flow - tank drain (please help)

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Old   December 7, 2011, 03:08
Post Unsteady flow - tank drain (please help)
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Hello Everyone,

For the last 2 weeks I have tried to model an unsteady flow with no viable results.

Problem description:

Create a 10 meter in diameter cylindrical tank with an outlet nozzle of 1 meter in diameter. How long does it take the fluid level to drop from 30meter above the tank outlet to 1 meter above the tank outlet?

The top of the tank is open to the atmosphere.

I have done the following:

- Created geometry in GAMBIT. (30m height, 10m diameter, w/nozzle 1m above bottom)

- Once in FLUENT:

Define/Operating Conditions/

-Pressure set at 101325 Pa
- Gravity check marked

Define/Boundary Conditions/

- Open top of cylinder: Vent Inlet @ 0 psig
- Nozzle exit: 1 flow rate


-All checked marked (1x10^-5)


-Time and delta time: print


- No initial conditions since at time zero draining has not begun.



PLEASE HELP!!! I am worn out from trying everything possible! (except the right approach)
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unsteady flow

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