Learning Forum

[tumulpurwar]

What boundary condition and approach I should take?

I have 4 pipes coming from sea (source tank) and these 4 pipes are taking water from sea with help of water pump(p1, p2, p3, p4) and put it to tank, which is in vertical height of say 6 meter from sea. I want know

Effective combined pump flow rate for this combination of piping system & parallel pump

Also flow rate at tank individually by pipes also

[Rob]

What information have you got?

[tumulpurwar]

Hello Rob
Thanks for commenting, I don't have yet now input for this project.
But I would like to explore and know, how many ways are there to approach it.
Like one time may be I know inlet velocity or mass flow rate
On other situation, I don't know inlet velocity or mass flow rate.
Just trying to explore different scenerio in internal pipe flow cases.

[Rob]

You will know something, that may be the flow rate OUT of the system, no reason not to use a suction (negative velocity) boundary. If the flow is constant density use velocity bc, it's more stable and only takes a minute or so to work out.

[Devin_Rana]

There are many types of boundary conditions used in ANSYS like velocity inlet and outflow, pressure inlet and pressure outlet, mass flow rate, inlet vent, intake fan, outlet vent, and exhaust fan.
The most used boundary conditions are velocity inlet and outflow, pressure inlet and pressure outlet, mass flow rate. Here we show some basics of these boundary conditions.

From your question....
Mass flow inlet-outlet boundary conditions
Mass flow inlet boundary conditions are used incompressible flows when the inlet mass flow rate is known. It is not necessary to use mass flow inlet boundary conditions for incompressible flows because density is constant for incompressible flows and velocity inlet boundary conditions will fix the mass flow.
For analysis of mass flow rate at the outlet,Mass flow outlet boundary conditions is used.
You can refer to this article regarding different types of boundary conditions and where they can apply https://www.cadsys25.com/2020/06/cell-zone-and-boundary-conditions.html

[Rob]

thanks for the post. As a slight correction, outflow isn't widely used any more. It's an old boundary setting that is superseded by pressure outlet: I think I last used it in FLUENT v4 in the early 00s.

[tumulpurwar]

Thanks both for giving answers, I will come back to this same post with queries as I start that project soon. (In next 2 weeks)