International Journal of Heat and Mass Transfer, Vol.135, 247-261, 2019
Complex transition of double-diffusive convection in a rectangular enclosure with height-to-length ratio equal to 4: Part II
The paper investigates numerical results of double-diffusive convection in a slim rectangular enclosure with horizontal temperature and concentration gradients. The case with the thermal Rayleigh number, Ra-T = 10(5), the Prandtl number, Pr = 1, the Lewis number, Le = 2 and height-to-width aspect ratio, A = 4 is considered. Effects of the buoyancy ratio of composition to temperature, N, on dynamical behavior, flow structure and heat and mass transfer efficiency are investigated carefully. The present results suggest that with the buoyancy ratio N increasing from 1 to 2, the flow of transition is a complex series of changes from the periodic to quasi-periodic, chaotic, periodic, and finally to laminar with concentration dominated. There are three types of periodic flows, the first one is simple periodic flow with single fundamental frequency (FF), the second one is periodic flow with FF and its integer multiple of frequencies (INTMF), the last one is the more complex periodic flow with FF, INTMF and its sub-harmonic frequency multiple (SFM). A new type periodical solution with reverse central symmetrical structure is captured in the present paper. Multi cells structures traversing between two vertical walls will produce salt figure phenomenon and benefit to enhance heat and mass transfer efficiency. (C) 2019 Elsevier Ltd. All rights reserved.