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two fluid, volumetric/mass flow rate at different volume fractions

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Old   November 26, 2014, 04:25
Question two fluid, volumetric/mass flow rate at different volume fractions
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Véronique Penin
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Hi Everybody,

Context : multiphasic turbomachinery (water : continuous fluid/air: dispersed fluid), frozen rotor, inhomogeneous Model, fluid dependant.

I have to run a lot of simulations with different volumetric flow rate at different volume fractions to compare with experimental results.

No problem with one-fluid calculation, where the convergence is checked by a monitor point MASSFLOW = massFlow()@S1 Outlet (the inlet condition is the mass flow on RI Inlet, and it easy to choose the mass flow rate corresponding to the experimental volumetric flow rate).

With the two-fluid simulation, I can't use the mass flow rate as an inlet boundary condition, so I use normal speed as inlet boundary condition.

My problem is the correspondance between the inlet velocity and the volumetric flow rate (checked by my monitor point and the mass flow rate) in function of the volume fraction.


How is calculated the "massflow()" with my two-fluid simulation in function of the volume fraction? (Is (alpha*rho_alpha + (1-alpha)rho_beta) * Velocity * Surface ?)
Or how can I set the inlet velocity to be sure that it corresponds to the good volumetric flow rate at a given volume fraction?


Thanks a lot

Véronique
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Old   November 26, 2014, 05:24
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Glenn Horrocks
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The CEL expressions are described in the documentation. But for massflow it is simply the density times normal velocity integrated over the boundary - where density and velocity are phase weighted.
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Old   November 26, 2014, 05:30
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Véronique Penin
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Yes, I read the documentation, but il was not clear for me.

Thanks to confirm that mass flow are phase weighted.

Véronique
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