# Reference pressure on Multiphase flow

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December 9, 2015, 07:50
Reference pressure on Multiphase flow
#1
New Member

M.A.
Join Date: Dec 2015
Posts: 6
Rep Power: 10
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!

I only have two domains: the casing, and the rotor. (see picture)
The whole rotor domain rotates.
Attached Images
 Capture34.jpg (111.2 KB, 17 views)

 December 9, 2015, 17:29 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,746 Rep Power: 143 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.

 Tags cfx, cross flow turbine, multiphase simulation