| Summary: | 碩士 === 中華大學 === 機械工程學系碩士班 === 98 === Numerical simulations are performed to investigate the effects of aspect ratio (AR = 0.2、1、5), Richardson number (Ri = 0.01、1、100), and inclination angle ( 0°～90°) on the flow structures and heat transfer in a air-filled (Pr = 0.71), two-dimensional (2-D) cavity where the flow is induced by a shear force resulting from the motion of the cooled upper lid combined with buoyancy force due to bottom heating. The governing equations for the 2-D velocity and temperature fields are discretized spatially into a fourth-order accurate compact form. Numerical results indicate that among the three aspect ratios studied the increase of inclination angle does not affect the flow structures and heat transfer when the flow is in a forced convection dominated regime (Ri = 0.01). However, when the flow is in a pure natural convection dominated regime (Ri = 100), the increase of inclination angle enhances the heat transfer rate, especially for AR = 1 and 5. The maximum heat transfer rate occurs at 75° and Ri = 100. In addition, the flow changes from a stable, laminar regime to an unstable, chaos regime under certain inclination angles. At these conditions, the total kinetic energy appears to be in periodic or non-periodic oscillations.
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