Jph. Sanders et I. Gokalp, SCALAR DISSIPATION RATE MODELING IN VARIABLE-DENSITY TURBULENT AXISYMMETRICAL JETS AND DIFFUSION FLAMES, Physics of fluids, 10(4), 1998, pp. 938-948
In recent years several transport equation models for the scalar dissi
pation rate have been proposed to replace the well known algebraic exp
ression based on equality of mechanical and scalar turbulent time scal
es. In this study various transport equation models are compared with
each other and the model equation of Yoshizawa [J. Fluid Mech. 195, 54
1 (1988)] is given special attention. The latter is shown to allow an
algebraic solution that is different from the classical ''equal-scales
'' algebraic model. The constants that appear in this equation are ass
igned values based on similarity behavior in turbulent jets and based
on studies of homogeneous isotropic turbulence. Both algebraic models
and the transport equation models are compared and applied to isotherm
al variable density jets and jet diffusion flames. It is found that ge
neral features, such as the behavior of scalar fluctuation intensities
of variable density turbulent jets are relatively well predicted by a
ll the models. Differences between the models exist regarding the pred
icted time scale ratios. (C) 1998 American Institute of Physics.