Effect of surface roughness on the thermal behavior of Schwarz-D TPMS lattice structures

In additive manufacturing (AM), triply periodic minimal surface (TPMS) structures are widely employed to construct compact, high-performance heat exchangers (HEs). However, surface roughness inherent to AM represents a major challenge for the practical application of TPMS heat exchangers. This study employs artificial surface roughness based on a perturbation-based model to replicate surface irregularities, thereby evaluating the effects of AM-induced surface roughness on heat transfer and fluid flow performance. The simulation results indicate that the roughness amplitude parameter A and spatial wave number w 2 will induce local convective heat transfer coefficient h concentration. The larger the A and w 2 , the stronger the concentration effect is. The performance evaluation shows that the TPMS lattice structure without surface roughness can achieve the highest overall heat transfer coefficient U , while exhibiting the lowest pressure drop. In terms of performance evaluation criterion j hot f hot 1 / 3 , structure without surface roughness outperforms others. This work demonstrates that the roughness-induced geometric deviations have a significant influence on thermo-hydraulic performance. For the investigated cases, the increased hydraulic penalty outweighs the heat transfer enhancement.