Optimal Thermal Design of CPU Heat Sinks: Numerical Study of Pin-Fin Geometry and Nanofluids

This study numerically investigates the thermal performance of a rectangular channel CPU heat sink using five micro pin-fin geometries (triangular, circular, square, parabolic, hexagonal) and two nanofluids (AI203-water and CuO-water). A 3D computational fluid dynamics (CFD) model was developed to analyze heat transfer characteristics under laminar-to-transient flow regimes (Reynolds number: 500–4000). The governing equations (continuity, momentum, energy) were solved using a finite volume method with a SST turbulence model. Results demonstrate that nanofluids significantly enhance the Nusselt number (Nu) compared to air, with Al203-water outperforming CuO-water. Circular pin-fins achieved the highest increase in Nu (67. 01 % at $\text{Re}=500)$, followed by hexagonal and square fins. Increasing AlO volume fraction (1–4 %) further improved Nu by up to 4.9%. The combined use of circular pin-fins and Al2 03 -water nanofluid is recommended for optimal thermal management in electronics cooling.