Heat transfer and entropy generation in oscillating lid-driven heat sinks with variable fin configurations

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This study investigates the hydrothermal characteristics and entropy generation within a heat sink subjected to oscillating lid-driven motion and featuring various fin configurations. The analysis focuses on the effects of the Strouhal number (St) and Richardson number (Ri) on heat transfer and entropy production. The current study was conducted over 14 frequencies (0 ≤ St ≤ 0.042), 3 Richardson numbers (0.1, 1, 10), and 6 distinct fin configurations. Using numerical simulations, the study reveals that the oscillating motion of the top plate significantly enhances the heat transfer rate, particularly at lower Ri values where forced convection predominates. Increasing the oscillation frequency improves Nusselt number (Nu) up to a certain point, beyond which further increases deteriorate Nu value. The oscillatory motion of the top plate enhances fluid mixing, boosting heat transfer by disrupting boundary layers and generating vortices that facilitate the exchange of mass, momentum, and thermal energy. The arrangement of fins plays a crucial role, with configurations 6 and 3, which have increased free space between fins, exhibiting higher rotational velocities and improved flow penetration, thus demonstrating superior performance. In contrast, configurations 5 and 2 performed the worst due to the height of the middle fin, obstructing fluid motion across the cavity. Entropy generation analysis shows that thermal entropy is the dominant contributor, increasing with lower Ri values due to enhanced heat transfer rates and temperature gradients. The findings provide valuable insights for optimizing heat sink designs and operating conditions to maximize heat transfer efficiency and minimize entropy generation, informing the development of more effective thermal management systems.