DOUBLE-DIFFUSIVE CONVECTION IN A ROTATING ANNULUS WITH HORIZONTAL TEMPERATURE AND VERTICAL SOLUTAL GRADIENTS

Abstract

A numerical study is made of double-diffusive convection in a rotating annulus. Motions are driven by the externally applied horizontal temperature gradient. The stable solutal gradient is aligned in the vertical direction. Parametric studies are performed in order to acquire an understanding of the qualitative character of the axisymmetric basic state of the resulting flow. The aim is to inquire as to the effect of rotation on the global flow structure. A high-accuracy pseudospectral numerical scheme is employed to integrate the axisymmetric incompressible Navier-Stokes equations. Computational results are presented to disclose the detailed fields of azimuthal and meridional flows, temperature, and solute. A total of nine parameter sets, produced by a combination of three values of stratification number and three buoyancy ratios, were dealt with in the computation. The Prandtl number was set Pr = 1.0, the thermal Rayleigh number Ra(T) = 10(5), and the Lewis number Le = 10.0. For a low buoyancy ratio, motions are vigorous, especially when the rotation effect is small, resembling a sidewall-heated pure thermal convection. In the interior, a linear temperature stratification and a well-mixed solutal field are seen. When the buoyancy ratio is moderate, the overall character of flow shows considerable dependence on the relative strength of rotation effect. For a large buoyancy ratio, the stabilizing solutal effect is dominant. The convective activities are very weak, and heat transfer is mostly conductive.