Homogenization-based optimal design of non-uniform lattice heat sinks: Comparative study on cell structures

Efficient thermal management is crucial for modern high-performance electronics, where compact, lightweight, and mechanically robust heat sinks are required. Lattice structures have recently gained attention as engineered porous materials that provide a large heat transfer area while maintaining mechanical strength. This study investigates how unit cell geometry and heat-sink height influence the design and performance of non-uniform lattice heat sinks developed using a homogenization-based topology optimization framework. Three strut-based lattice units (CC, BCC, and FCC) and two heat sink heights were examined under identical pressure drop and volume constraints in forced convection conditions. Homogenized analyses revealed clear differences in permeability and form-drag behavior among the unit geometries, and these properties directly shaped the resulting non-uniform material distributions. Evaluations of the mapped explicit lattices using the thermal efficiency index showed that the preferred unit cell depends on the heat-sink aspect ratio: in the tall sink, CC outperformed BCC and FCC by 2.4% and 12.4%, respectively, whereas in the short sink, FCC exceeded CC by 7.2% and BCC by 1.7%.