Unsteady flow - tank drain (please help)
 

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/Models/Solver/Unsteady
Define/Models/Viscous/k-epsilon
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

Solve/Monitors/Residuals

-All checked marked (1x10^-5)

Solve/Monitors/Statistics

-Time and delta time: print

Solve/Initialize/Initialize

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

Solve/Iterate

- NOT SURE WHAT TO DO HERE!:eek:

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