Effect of aspect ratio and nonuniform temperature on mixed convection in a double lid-driven cavity

Abstract

The impact of aspect ratio and nonuniform temperature on mixed convection in an enclosure is examined numerically. The chosen shape is an enclosure with a sinusoidal temperature T_H in its lower wall, while the upper wall is considered adiabatic. The sidewalls of the cavity move at a descending speed with a uniform temperature T_C. The inspection is performed for different Richardson numbers and aspect ratios (AR) varying from 0.25 to 5, while the numbers of Prandtl (Pr = 0.71) and Grashof (Gr = 10⁴) remain constant. The isothermal, streamline, and Nusselt numbers flow distributions inside the cavity are highlighted and discussed. Compared to uniform heating, significant changes in the flow rate are observed when receiving nonuniform heating on the lowest cavity surface. Two cells of flow rotating in opposing directions are formed inside the cavity when the cavity aspect ratio AR = 0.25. When the cavity aspect ratio becomes higher than the unity, these cells change with the development of Ri; they take an oval form and move to the heated side. The non-uniform heating yielded a sinusoidal localized thermal exchange rate with the lowest amounts at the edges and considerable amounts at the bottom center (Ri = 1 and 100).

Keywords:

• Aspect ratio
• double lid-driven cavity
• mixed convection
• thermal exchange