In the present study, the ensuing natural convection phenomenon inside a heated enclosure filled with disconnected, discrete solid blocks, and under time-periodic heating in the horizontal direction is investigated numerically. This configuration is akin to several practical engineering applications, such as in the food (baking) industry, metal parts (heat treating) industry, and containerization (storage and transportation) of discrete solid goods. Because of the relative large size of the solid bodies placed inside the enclosure, a porous medium approach is not appropriate in the present case. Hence, the solid and fluid constituents within the enclosure are viewed individually and modeled using continuum balance equations, with suitable compatibility conditions imposed at their interfaces. The periodic heating is simulated by imposing a sinusoidal time-function on the hot wall temperature, while maintaining the cold wall temperature constant. Results are presented in terms of surface-averaged (hot and cold) Nusselt numbers, time-varying energy capacity (equal to the thermal energy stored inside the enclosure), isotherms and streamlines, for Ra varying from 103 to 107, Pr = 1 and 36 uniformly distributed, conducting and disconnected solid square blocks. The results, focusing on the time-periodic regime, indicate the effect of varying Ra on the convection process. As Ra increases, the dynamic capacitor performance of the enclosure tends to be enhanced.

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