Effects of cavity–slip boundary interactions on microscale flow and heat transfer characteristics

Microscale flow and heat transfer underpin the thermal management of high-density microelectronics, microreactors and compact heat exchanger. Existing studies rarely examine the coupled influence of different factors on both hydrodynamic resistance and convective heat transfer, leaving a gap in guidance for integrated design. This work systematically quantifies how cavity–slip boundary interactions to alter the thermohydraulic performance. The results show that the slip boundary smooths the near-wall velocity profile and reduces viscous dissipation under low flow conditions, while they enhance momentum transport and intensify inertial convection at higher flow conditions, leading to more complex effect of cavity geometry. Cavity depth promotes recirculation that enhances mixing but exhibits a non-monotonic trend under no-slip conditions. The dependence becomes monotonic once the slip boundary is introduced, with flow resistance and heat transfer decreasing consistently with deeper cavities. Cavity width exerts a dual role: larger cavities act as low-shear sidewalls and reduce flow resistance in the absence of slip boundary, but when slip boundary is introduced wider cavities generate stronger flow disturbances and higher resistance at large flow rates. The optimal thermohydraulic performance occurs with a maximum factor of 1.89 in the case of a narrow cavity combined with a large slip length. Our findings demonstrate that optimal microscale cavity design requires concurrent tuning of slip boundary, cavity geometry, and flow condition. These insights establish a physical basis for the rational design of high-efficiency microscale thermal management systems.