Numerical Evaluation of Roughness Effect on the Thermal Performance of the Schwarz-P-Based TPMS Heat Sink

Triply Periodic Minimal Surfaces (TPMSs) offer compact geometry and enhanced thermal performance, making them attractive for heat sink applications. However, their complex structures pose manufacturing challenges, typically addressed through additive manufacturing (AM), which inherently produces rough-textured surfaces. While surface roughness significantly influences heat transfer, most numerical studies assume smooth surfaces. While some earlier studies have established the impact of surface roughness on heat transfer, they often overlook the overestimation of heat transfer enhancements. This oversight leads to inaccuracies in predicting the actual thermal performance of these structures. By addressing this gap, this work provides an accurate assessment of the influence of surface roughness on TPMS heat sinks thermal performance. A computational fluid dynamics (CFD) model using the SST k-ω turbulence model with surface roughness and thermal correction is developed. The findings demonstrate that surface roughness enhances thermal performance; for instance, a Schwarz-P heat sink with roughness of 20 μm shows an improvement of approximately 18%. In addition, neglecting the thermal correction in the surface roughness model leads to an overestimation of the heat transfer coefficient by about 13% for the same roughness level. The superior thermal performance of rough-surface heat sinks is attributed to higher effective heat transfer area and increased turbulent kinetic energy, which collectively enhance the heat transfer coefficient, but at the expense of a higher pressure drop. The study provides valuable insights but also highlights the scope for further research. Future investigations should prioritize validating numerical results through experimental testing, exploring alternative roughness models, and incorporating additional empirical relationships to translate measured surface roughness values effectively.