Combined Forced- and Natural-Convection Heat Transfer in Horizontally CounterRotating Eccentric and Concentric Cylinders

Abstract

The present investigation focuses on the numerical simulation of mixed-convection heat transfer in a horizontal annulus configuration. The flow is set to operate in the laminar regime under steady-state condition. A counterrotating cylinder arrangement is considered while the inner cylinder is heated. A nonuniform grid size is employed in the radial direction to capture the velocity and temperature distributions near the walls. Furthermore, discretization of the governing equations is achieved using a finite-element scheme based on the Galerkin method of weighted residuals. The flow and thermal characteristics are explored for a pertinent range of dimensionless velocity ratio, gap-width ratio, and Rayleigh number given by 0 ≤ κ ≤ 5, 0.5 ≤ σ ≤ 5.0, and 103 ≤ Ra ≤ 105 while eccentricity factor ϵ(r, φ) is varied over various radial and angular positions. The local Nusselt number distributions along the cylinders are documented over a range of operating conditions.