Global stability analysis of the natural convection between two horizontal concentric cylinders

In this investigation, the 2D flow between two horizontally positioned concentric cylinders (gravity perpendicular to axis of cylinders), where inner cylinder is kept at constant temperature Ti higher than outer border To, analyzed. Buoyancy forces initiate movement fluid and generated studied in a fixed geometry for values Prandtl numbers (Pr) 0.01 1, Rayleigh (Ra) 102 5·106. To solve problem, Chebyshev-Fourier spectral code developed polar coordinates (r,?) respectively, complete map steady-state solutions obtained regions with multiple are identified. Later, global stability study stationary carried out, providing transition curve unstable areas as function control parameters problem (Pr,Ra). Finally, check results, temporal evolution simulations accomplished several cases dual presented, finding intermediate almost solutions, demonstrating that there exist typically single oscillating plume or double (depending on parameter space), some them have heat transfer coefficients, which may be interesting alternatives improve exchange systems by means passive techniques.