Controlling flow separation and enhancing heat transfer in topographical microchannels via wall slip

Corrugated microchannels with superhydrophobic walls can become key enabling technologies in various engineering applications, especially in electronic cooling and heat exchange devices. The present study employs the finite-element method to investigate laminar forced convection heat transfer of water in a topographically corrugated channel. The analysis includes sinusoidal wall temperature heating and varying slip length as boundary conditions on the wavy walls. Under fully no-slip conditions, flow separation occurs in the diverging section of the channel at several Reynolds numbers (1-1500) for pattern amplitude-to-pitch ratios α>0.1. This study effectively employs the concept of a Robin-type slip boundary condition to attenuate flow separation and enhance heat transfer performance. The results reveal that wall slip effectively reduces the intensity of flow separation by lowering the minimum streamwise velocity in the recirculation region across a range of Re from 1 to 1500. For example, at a large dimensionless slip amplitude (B_m) of 0.8, flow separation is effectively mitigated. The product of Re and local skin friction coefficient decreases as B_m increases. A notable reduction in pressure drop is observed in comparison to fully no-slip flow. For Re ranging from 1 to 500, the pressure drop is reduced by approximately 43%–48% for small Re and by 50%–65% for higher Re compared to the no-slip flow. The present study is compared with the literature-based experimental and numerical results. Additionally, wall slip enhances heat transfer parameters, leading to heat transfer factor, total entropy generation, and higher Nusselt numbers compared to the no-slip case. The implementation of the Robin-type slip boundary condition enhances thermal entropy generation and reduces low-intensity Bejan number regions in the trough, resulting in a more uniform and efficient entropy distribution compared with the conventional no-slip case. Furthermore, Smaller wall temperature wavelengths significantly amplify entropy generation, with λ_th=0.25 yielding the highest N_Total, while the introduction of slip flow further improves total irreversibility by approximately 30%–57% compared to conventional boundary conditions. The investigation demonstrates that sinusoidal slip and wall temperature heating are more effective for enhancing heat transfer than conventional boundary conditions.