Alternative to the Formulation of the Equations of Turbulent Motion of a Variable-Density Fluid.

The various methods applied to the formulation of the open set of equations governing the turbulent motion of variable-density fluids, are reviewed. Then, using conventional averages, it is proposed that the convective correlations be split into three groups and that a flux term based on the instantaneous value of the fluid density be introduced. It is shown that in different cases the double correlations including the density fluctuations are directly linked to this flux term in such a way that the system of second-order equations is reduced to the constant-volume situation.