Wanted buoyancy constants in k-epsilon model
 

Generation of turbulence due to buoyancy sometimes is included in k-e model "... +c1(eps/k)(1-c3) g mu / (rho sigma _ h) * d rho/d z +... ", where c1=1.44, g=9.8, etc. Please who can tell typical (Mach=0) values two constants c3, sigma_h and appropriate references?

Thank you. Grigory.

Re: Wanted buoyancy constants in k-epsilon model
 

As far as I understood, you address the C3 empirical constant, that appears in the epsilon equation of k-epsilon turbulence model. C3 is connected with the buoyancy influence on turbulence. (your formula-fragment does not match with formulations I know)

Rodi (Turbulence Models and Their Application in Hydraulics 1980) discusses it and suggests a value of 0.8 connected wich an appropriate formulation of flux Richardson number. Recent investigations I read about (Sanders et al. Int. J. Heat Mass Transfer No.4(1997), Char+Hsu Int. J. Heat Mass Transfer No.12(1998), Hwang+Chiang J. Fluids Eng. Dec.1995 ), leave it out or set it to zero.

I need to find out about this problem myself. So if somebody in this forum knows more, please be so kind to send a note.

Jens Wyrwa