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Simran Saini January 31, 2007 12:32

Dear all

I am facing a problem choosing the type of boundary conditions. Problem Statement: There is a tank filled with water. A pipe has its outlet at center at some distance above the bottom of the tank. The water enters the tank from this outlet. Along side the outlet is an inlet(within the tank). Water from this inlet is taken out from the tank and then pumped backed to the tank through the pipe outlet. I am using Fluent 6.1.18. The tank and the pipe are meshed seperately using Gambit. Can anyone please suggest the suitable boundary condition at the pipe inlet and outlet(within the tank).


Nak January 31, 2007 15:18

Re: Recirculation
Where is the inlet (within the tank) located? Is it on one of the side walls, or on the bottom ? Or is it parallel to the other, when you say "along-side"?What are the diameters of the inlet and outlet pipes?

I guess mass flow inlet and pressure outlet should work.

Ragh January 31, 2007 17:44

Re: Recirculation
From the statement, it is not clear at all that what you really want to do. Do u want to model flow in the tank or pipe or both as a unit. The outlets and inlets will be different if u consider each of the 3 cases stated above. Do u have pressure jump condition at the pump ? What exactly do u want to do by modeling this problem? As by your problem statement, it seems to me that 1 D analysis should be sufficient to analyse the problem...

Simran Saini February 1, 2007 03:02

Re: Recirculation
Problem Statement: I have got a tank of size, 1000 litres. It has got inlet and outlet pipes of diameter 5 inch at the bottom and top respectively. To enhance the turbulence, I am planning to recirculate a part of water through a recirculating pipe of diameter 1 inch (recirculation can be achieved using centrifugal pump placed in line with the circulating pipe. I am not interested in modeling the centrifugal pump but effect of pumping can be maintained by imposing some boundary condition at inlet OR outlet of the recirculating pipe.) Recirculating pipe is partly inside and partly outside the tank. Outlet of recirculating pipe is at a distance of 12 inch from the base at the centre of the tank and inlet is at a distance of 10 inch from the base towards the left side wall. Early response is appreciated. Thankyou

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