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 Ginganinja February 2, 2011 10:12

Piping dilemia

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Hi there, I'm a beginner to CFD, with only a few months of experience, I've analysed compressible flow through a chocked convergent/divergent nozzle, that's about it. The geometry software I use is gambit 2.2 and Fluent 6.3 for CFD.

I'm trying to model a buffering system used in a Photo-voltaic pumping system. Power is supplied to a centrifugal pump and it isn't assumed to be constant because of environmental factors such as weather which affect the performance of photo-voltaic cells. This buffering system is intended to ease flow fluctuations caused by power fluctuations.

In essence here, referring to attachment, (sorry its a rough schematic)

I am only interested in modelling the two cases when valve 1 and valve 2 are closed, and when valve 1 is open and valve 2 is closed.

Initially when Valve 1 and valve 2 are closed flow is induced along a pipe by a centrifugal pump. The fluid enters the Accumulating chambre (this is similar to a capacitor if you were thinking of an electrical analogy). The purpose of the chambre is to increase specific volume (this is achieve by having the chambre full of rubber balls, which compress when flow enters and increase specific volume or by modelling it as a cyclinder with a piston on top.)

When the accumulating chambre reaches a certain pressure or specific volume, I want valve 1 to change from closed to an open state. So that flow can continue vertically to a storage tank. Will I need to write a user define function on a boundary wall for this instance? I'm unsure how to go about modelling this. So colleagues have mentioned a dynamic mesh, is this correct?

I'm assuming that the fluid is water, incompressible, adiabatic, isentropic, fluid flow is instaneously, the valves operate perfectly/instaneously, 2D and piping walls are frictionless. Perhaps I'll start test as steady flow and then move on to more complicated models.

thanks for taking the time to read this. I hope it clear and easy to understand and I look forward to hearing your input.

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