Hi all, i ask in advance sorry for my bad english, i hope you will understand my question. I'm studying the motion of a plume fluid in a fluid ambient, with ρ(plume) > ρ(ambient). Afterwards there si a transport of fluid ambient as an effect of the turbolence caused by the viscosity between the two fluids. This is, somehow, featured by the Alpha coefficient (entrainment) My request is: can you explane to me, what physically represent this number? What i have to imagine when i want to figure out the entrainment? Wich is the formule? Thank for your time!