© 1980 by Oxford University Press
THE STABILITY OF FREE CONVECTION IN A HORIZONTAL CYLINDRICAL ANNULUS
( Department of Mathematics, Imperial College London SW7 2BZ )
Fluid fills the annulus between two concentric horizontal cylinders maintained at constant temperatures. When the inner cylinder is hotter than the outer a steady flow results but this may become unstable to small perturbations for a sufficiently large value of the Rayleigh number. We examine the onset of this instability when
, the ratio of gap width to the radius of the inner cylinder, is small, by expanding in powers of
and employing a WKB formulation for the perturbed solution. Values of the critical Rayleigh number at which instability first occurs are obtained for several values of the Prandtl number and a comparison with experimental and numerical results is made.