Selection of Density for the Granular Phase in the Euler-Euler Method
 

I am using the Euler-Euler method with the objective of simulating the interaction between a particulate and fluid phases.

As the air flows over a packed powder bed an aerosol is created.

I am confused as to what density to use: that of bulk powder (720 kg/m^3), as this is the initial state, or that of aerosolised powder (approaching 1.225 kg/m^3)?

I do seem to be getting more realistic results by setting the density value significantly lower than that of bulk powder.