Fluid dynamic investigation of a topology-optimized liquid-cooled heat sink for enhanced performance

At the heart of single-phase chip cooling lies the optimization of heat sink fins. Topology-optimized fin patterns efficiently dissipate high heat fluxes while maintaining a lightweight design. This article undertakes a comprehensive numerical investigation to assess the thermo-hydraulic characteristics of an internally developed topology-optimized fin pattern. The global performance assessment reveals that the Nusselt number and friction factor with topology optimized design is 93% higher and 38% lower compared to optimized straight channel design. Unlike many topology-optimized designs prevalent in literature, the present design exhibits a synergistic enhancement in both thermal and hydraulic performance. The research reveals the local flow characteristics that underpin the superior performance of the topology-optimized design. These include the formation of Dean's vortices, re-initialization of the boundary layer, and mixing due to secondary flow. Through comprehensive assessments of local axial velocity and temperature profiles at various points along the length, the study elucidates nuanced dynamics of hydrodynamic and thermal boundary layer thicknesses, as well as near-wall temperature gradients. The fin pattern with sectional fins helps in lowering junction temperature by providing cross-flow mixing, facilitating enhanced convective heat transfer. Furthermore, the pivotal role played by an additional row of sectional fins in mitigating pressure drop by bifurcating the flow into two or more streams is clearly illustrated. These features render the topology-optimized design suited for single-phase chip cooling applications experiencing higher flow rates, thereby yielding tangible benefits in terms of energy savings and augmented efficiency.