Three-dimensional natural convection in spherical annuli

Abstract

Natural convective fluid motions in the gap between two concentric non-rotating spheres are numerically studied. The case of homogeneously heated inner sphere and cooled outer sphere is considered for the radial aspect ratio π = 0.714 and Prandtl number Pr = 0.7. The natural convection problem is characterized by the Rayleigh number associated with the heat transfer within the fluid. For small values of the Rayleigh number an axisymmetric single vortex of crescent shape is formed as the basic flow. By increasing the Rayleigh number, flow patterns with banana-type cells, oriented in north-south direction and aligned in the azimuthal direction, are formed. Various characteristics of these flows as well as their transient evolution are investigated.