NUMERICAL-SIMULATION OF SUPERCRITICAL HADLEY CIRCULATION, WITHIN A POROUS LAYER, INDUCED BY INCLINED TEMPERATURE-GRADIENTS

Simulations of supercritical Hadley circulation, induced by horizontal and vertical temperature gradients imposed on a fluid saturated porou s medium layer, are performed numerically. The mathematical model conf ines the simulation to longitudinal flow in which secondary cell axes are transverse to the direction of the Hadley circulation. Numerical r esults agree well with critical (bifurcation) states predicted theoret ically via linear stability analysis. For horizontal Rayleigh number, Ra-b, smaller than 40 and vertical Rayleigh number, Ra-v, beyond a cri tical value, results indicate that the flow evolves from subcritical H adley circulation to supercritical Horton-Rodgers-Lapwood-like flow. A switch in the preferential heat transport direction, from horizontal to vertical, parallels this evolution. For Ra-h beyond 40, numerical s imulations at supercritical regime reveal the appearance of a travelin g wave characterized by continuous drifting of flow cells in the direc tion opposite to the applied horizontal temperature gradient, that is towards the cooler temperature.