Impact of geometric complexity on thermo-hydraulic performance of additively manufactured pin-fin arrays

This study experimentally investigates the impact of geometric complexity in additively manufactured pin-fin arrays on their thermo-hydraulic performance. Eight designs, each representing increasing levels of pin-fin array complexity defined by a newly introduced complexity parameter, are selected and manufactured using laser powder bed fusion additive manufacturing. Once fabricated, the specimens are thoroughly characterized using computed tomography to understand the difference between intended and fabricated designs. The complexity parameter is found to accurately capture the rank-order among designs. Experiments spanning duct Reynolds numbers from 5000 to 40,000 quantify key thermal-fluid metrics, including pin-fin heat transfer ( Q ), pressure drop ( ΔP ), friction factor ( f ), Nusselt number ( Nu ), and efficiency index ( η ). All arrays outperform the cylindrical reference in Q and ΔP , with top designs achieving improvements of 84% and 76%, respectively. Low-complexity arrays exhibit the largest reductions in friction factor, up to 52.2%, while high-complexity arrays maintain low drag despite higher pin-fin counts due to the favorable shape profiles. Increased array complexity slightly reduces Nusselt number due to expanded surface area, revealing a trade-off between hydraulic efficiency and convective enhancement. In summary, these findings highlight the advantages of leveraging additive manufacturing to realize complex pin-fin geometries that would be challenging or impractical to produce using conventional manufacturing methods.