Thermo-fluid dynamics and synergistic enhancement of heat transfer by interaction between Taylor-Couette flow and heat convection.

This study experimentally and numerically investigated the thermo-fluid dynamics of Taylor-Couette flow with an axial temperature gradient from the chemical engineering perspective. A Taylor-Couette apparatus with a jacket vertically divided into two parts was used in the experiments. Based on the flow visualization and temperature measurement for glycerol aqueous solutions with various concentrations, the flow pattern was classified into six modes: heat convection dominant mode (Case I), heat convection-Taylor vortex flow alternate mode (Case II), Taylor vortex flow dominant mode (Case III), fluctuation maintaining Taylor cell structure mode (Case IV), segregation between Couette flow and Taylor vortex flow mode (Case V) and upward motion mode (Case VI). These flow modes weremapped in terms of the Reynolds and Grashof numbers. Cases II, IV, V and VI are regarded as transition flow patterns between Case I and Case III, depending on the concentration. In addition, numerical simulations showed that in Case II, heat transfer was enhanced when the Taylor-Couette flow was altered by heat convection. Moreover, the average Nusselt number with the alternate flow was higher than that with the stable Taylor vortex flow. Thus, the interaction between heat convection and Taylor-Couette flow is an effective tool to enhance heat transfer. This article is part of the theme issue 'Taylor-Couette and related flows on the centennial of Taylor's seminal Philosophical Transactions paper (Part 2)'.