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Reference pressure on Multiphase flow

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Old   December 9, 2015, 07:50
Question Reference pressure on Multiphase flow
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Good Day guys.

I'm simulating a multiphase, cross flow turbine, but im relatively new to the software.
My site conditions are 10 meters of Head and 16 kg/s of flow rate.

In my setup, i have inputted the 16 kg/s flowrate at the outlet, and the 10 meter head on the inlet; (i converted the 10 meter head, as the corresponding pressure of 98.1 kPa)

My question is with respect to the reference pressure:

if my reference pressure is 1 atm for the whole setup, the does that mean i will input 98.1 kPa to the inlet?
(as opposed to if my reference is 0 atm, then it will be "98.1 kPa + 101.325 kPa" right?

My run keeps on adding wall during the solving so i do not know if I am wrong in the overall physics of the setup.
Thank you very much!

Additional information:
I only have two domains: the casing, and the rotor. (see picture)
The whole rotor domain rotates.
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Old   December 9, 2015, 17:29
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Glenn Horrocks
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Your inlet condition looks OK. Make sure you look at the free surface flow over a bump tutorial for some ideas about how to model free surface flows and reference conditions.

Your outlet boundary will be a problem. It is likely there will be lots of splashing, drops and bubbles flying in all directions so imposing a boundary here is difficult. It means you probably will get some reverse flow and hence the walls. Also - as you have defined a flow rate, how have you handled the flow rate between the two phases?

You might need to change your outlet boundary. For instance you could let it splash into a water pool and you take a submerged outlet from that which will be just water phase.
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cfx, cross flow turbine, multiphase simulation

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