[Sripadaraja]

Dear all,

I am modeling a multiphase simulation with VOF model. The primary phase is oil and the secondary phase is water. I am trying to introduce a surfactant using User Defined Scalar in Fluent. I am using the surfactant concentration value (0.2) as UDS value at the inlet. I have two questions:

1. Should we multiply concentration with the density of fluid before specifying as UDS value at the inlet.
if yes then which density continuous phase density or surfactant density?

2. While specifying UDS diffusivity in material properties should we multiply it with the density of fluid?
if yes then which density continuous phase density or surfactant density?

I am attaching the image of my model for reference.

Thanks