[MissCFD]

Does anyone confirm me what the variables below correspond:

- Mass-Water is for Continuity Equation of the Water ?
- Mass-Vapor is for Continuity Equation of the Vapor ?
- P-Vol is for Volume Conservation Equation ?

(These variables can be seen each iteration of a simulation)


And when my domaine Imbalance exceed 1% like below, it is not good, right?

+--------------------------------------------------------------------+
| Mass-Water-Domain dt |
+--------------------------------------------------------------------+
Boundary : AirInlet 1.5649E-14
Boundary : outlet -3.6559E+02
Domain Interface : bl dt (Side 2) 3.9123E+02
-----------
Domain Imbalance : 2.5637E+01

[ghorrocks]

Mass-Water is the mass fraction equation for water.
Mass-Vapor is the mass fraction equation for vapour.
P-Vol is the pressure correction/mass conservation equation.

A domain imbalance of more than 1% MAY indicate inadequate convergence. You need to do a sensitivity study to find out in your case whether that is acceptable for not. But for most applications the 25% imbalance you indicate would be unacceptable.

[MissCFD]

Thank you very much for your response.

For a good understanding:

- if there are an imbalance of 25% in the mass fraction equation for water that means that there are more mass that goes in or out of this domaine, right ?

- if there are an imbalance of 25% in the W momentum equation for water that means that the equation is not correctly applied, right ?

Originally Posted by ghorrocks

Mass-Water is the mass fraction equation for water.
Mass-Vapor is the mass fraction equation for vapour.
P-Vol is the pressure correction/mass conservation equation.

A domain imbalance of more than 1% MAY indicate inadequate convergence. You need to do a sensitivity study to find out in your case whether that is acceptable for not. But for most applications the 25% imbalance you indicate would be unacceptable.

[ghorrocks]

An imbalance in a mass fraction equation means that conservation of that mass fraction has not been achieved, that means that the sum of all mass flows does not equal zero.

An imbalance in the momentum equation means that momentum is not conserved. Momentum is mass*velocity in its simplest sense.

[Meister]

[QUOTE=MissCFD;660955]Thank you very much for your response.

For a good understanding:

- if there are an imbalance of 25% in the mass fraction equation for water that means that there are more mass that goes in or out of this domaine, right ?

It depends on your setup. If you use Multiphase with Cavitation, water is able to evaporate (water enters the domain but doesn't quit it anymore). If your setup is also transient you haven't yet established a steady state status -> It doesn't mean that your simulation is unphysical.