Effects of groove geometry around pin-fin perforation circumference on thermohydraulic behavior of pin-fin heat sinks under turbulent flow

The thermohydraulic performance of perforated pin-fin heat sinks (PPFHS) with different groove geometries around pin-fin perforation circumference is numerically investigated using ANSYS Fluent under turbulent flow conditions with Reynolds numbers ($Re$) ranging from 24,484 to 55,088. Four groove geometries—trapezoid, half-circle, rectangle, and triangle—are assessed for their effects on convective heat transfer efficiency, hydraulic resistance, and overall thermohydraulic performance. The groove sizes are designed to maintain a consistent air-solid interfacial surface area to total volume ratio across all configurations. The study finds that the trapezoid-grooved PPFHS exhibits the highest Nusselt number ($Nu$), achieving improvements of 11.8 %–20.9 % compared to the ungrooved PPFHS over the investigated $Re$ range. The half-circle, rectangle, and triangle grooves show $Nu$ enhancements of 10.9–20.2 %, 10.9–20.1 %, and 9.87–18.6 %, respectively. Friction factor reductions range from 4.35 to 8.57 %, 4.22–7.71 %, 3.10–6.62 %, and 0.87–5.05 % for the trapezoid, half-circle, rectangle, and triangle grooves, respectively. The thermal performance factor ($TPF$) of the trapezoid-grooved PPFHS is the highest, with improvements of 13.5–24.5 % over the ungrooved design, followed by the half-circle (12.5–23.4 %), rectangle (12.1–22.9 %), and triangle (10.2–20.7 %) grooves. While $TPF$ increases with $Re$, a diminishing rate of enhancement is observed at higher $Re$. The superior performance of the trapezoid groove is attributed to its ability to promote the most efficient airflow through the perforations while maintaining the lowest perimeter-to-cross-sectional area ratio.