Learning Forum

[youssef.badran]

Hello,

I ran a simulation involving three phases: water, air, and particles by coupling Rocky with Fluent, but the liquid volume was changing over time, indicating a mass conservation problem.

I performed the same test using the Discrete Phase Model in Fluent and did not observe this issue; the liquid volume remained constant.

Could you please inform me of the possible reason for this mass conservation problem when coupling Rocky with Fluent?

[Lucas Bertollo Baggio]

Hello Youssef, 

please check on the Solver | Advanced | CFD Coupling option Use 2023R2 Cell Volume Fraction Update Approach (does not displace fluid). This flag must be cleared (unchecked) to allow for fluid displacement. 

 

When enabled: The previous time-step solid fraction field is patched with the current solid fraction field, therefore eliminating any solid fraction variation influence on the solution. When the particle changes phase, it behaves as if it was already there.

When disabled: The solid fraction field variation is consider. Particles will displace fluid when changing cells or cell zones.

 

regards,

Lucas

 

[youssef.badran]

Thank you very much for your suggestion and explanation !

It seems that your suggestion has solved the mass conservation issue.