Entrainment Coefficient - Dynamics of Fluids

[Wall]

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? which is the formule?

Thank for your time!

 

[boneh3ad]

This is a rather niche topic within fluid mechanics. Have you tried checking out any relevant research papers or textbooks on the topic?

 

[Wall]

Hi, thanks for your reply! Yes, I did read those:

Effect of Background rotation in turbulent line plumes
http://journals.ametsoc.org/author/Fernando%2C+H+J+S and http://journals.ametsoc.org/author/Ching%2C+C+Y

Development of a point plume in the presence of background rotation
H. J. S. Fernando, R-r. Chen, and B. A. Ayotte

The motion of Turbulent thermal in the presence of background rotation

http://journals.ametsoc.org/author/Ayotte%2C+Barbara+Anne and http://journals.ametsoc.org/author/Fernando%2C+Harindra+J+S

I think i did understand what the entrainment is, but i don't its formula. I mean, i don't know its definition.

 

[boneh3ad]

Variable-density turbulence is an active area of research and is what is occurring in the situation you outline, but the specifics of your plume situation and its related analysis are not something with which I have any experience.

I do know of one recent paper about experiments on turbulent jets with differing densities. I don't know if this work would be relevant directly to what you are doing, but perhaps it could point you in the right direction.

dx.doi.org/10.1017/jfm.2017.379

 

[Wall]

Thank you so much, and thank you for your time, it will help me for sure!