Variable Density Flows Computed by a Second-Order Closure Description of Turbulence

An incompressibl e fluid, with the influence of the variable density coming through a Boussinesq buoyancy term, is considered using a second-order closure approach to turbulent flow. This technique successfully incorporates the strong influence of stratification for a number of flows. Particular flows which are computed and compared with experimental data are: 1) stratified shear flow with homogeneous turbulence; 2) free convection bounded by a stable density gradient; 3) wakes in a medium with a stable density gradient; and 4) the atmospheric boundary layer where the flow oscillates from stable to unstable conditions in a typical day. Nomenclature / = coriolis parameter FD = wake Froude number based on diameter gi = general acceleration vector k = coefficient of laminar diffusion for temperature perturbation