Abstract
In the present investigation, the evolution of homogeneous and stratified turbulence under a horizontal and a vertical shear is deliberate by coupled second-order model SSG-SL. This model is a result of a combination between the Speziale, Sarkar and Gatski model (SSG) and the Shih and Lumley model (SL). Horizontal shear and vertical shear are related to the angle between the shear and the vertical gradient of stratification; theta = pi/2 and theta = 0, respectively. This study is performed for different values of Froude number Fr ranging from 0.35-1.11. The SSG-SL model confirms the asymptotic equilibrium states for various physical parameters governing the problem (b(12), b(11), epsilon/KS, (rho u(2)) over bar, K/E and K-rho/E) for two shear orientations (theta = pi/2 and theta = 0). A comparison between findings using the present coupled model of SSG-SL and those by Direct Numerical Simulation of Jacobitz (DNSJ) [Jacobitz F, Sarkar S. A direct numerical study of transport and anisotropy in a stably stratified turbulent flow with uniform horizontal shear. Flow Turbul Combust. 2000;63:343-360.; Jacobitz F. A comparison of the turbulence evolution in a stratified fluid with vertical or horizontal shear. J Turbul. 2002;3:1-18.] is carried out. For the horizontal shear related to theta = pi/2, an excellent agreement between predictions by the SSG-SL model and the results of DNSJ [Jacobitz, Sarkar;Jacobitz] is detected for turbulent thermal and dynamic fields.