Natural convection in a horizontal annulus driven by a heat generating fluid

Abstract

Characteristics of laminar natural convection in a horizontal concentric annulus under non-uniform heat flux distribution along the inner cylinder, which is not known a priori, are parametrically investigated. The non-uniform heat flux distribution along the inner wall of the annulus is determined by an interaction between the flow of fluid with heat sources in the inner cylinder and the one without heat sources in the annulus; the thickness of the separating wall is considered either finite or negligibly thin, and both cases are analysed and compared with each other. Parametric studies have been carried out to investigate the effects of Rayleigh number, Prandtl number and diameter ratio on the flow characteristics and the heat transfer. It is found that the thermal field and the heat transfer pattern in the annulus with non-uniform boundary condition are different from those with uniform temperature distribution along the inner wall, but the flow characteristics are similar to each other. It is also found that for small Rayleigh numbers and diameter ratios, the temperature distribution in the radial direction and the heat flux distribution along the boundaries are quite similar to those of pure conduction in the annulus with uniform temperature boundary conditions, but it is quite different from each other for large Rayleigh numbers and diameter ratios.