Learning Forum

[rubenw]

Hi,

I am using the Multi-Fluid VOF model to simulate a turbulent bubbly-like flow. The symmetric drag model is Ansys' default drag model for the Multi-Fluid VOF model, and is recommended for flows in which the secondary (dispersed) phase in one region of the domain becomes the primary (continuous) phase in another, which seems suitable for my application. This drag model uses volume averaged density and viscosity and uses an average diameter d_pq=(dp+dq)/2. I assume the dp is the (bubble) diameter you specify when specifying the secondary phase, but I was wondering how Fluent knows the dq, as you cannot enter any diameter for the primary phase when specifying the phases. I assume dq in this case would denote the droplet diameter?

Thanks in advance!

[Amine Ben Hadj Ali]

The documentation tells that in case you have only one secondary phase dp=dq.

[rubenw]

So in what case would it account for a separate dp? How would you define the second secondary phase, and how can you define the dq in that case? As the symmetric drag model is recommended for flows in which the secondary (dispersed) phase in one region of the domain becomes the primary (continuous) phase in another, I would say that you should be able to specify a dispersed diameter for both phases.