With the high integration of electronic chips, heat dissipation has become an increasingly prominent issue. Additive manufacturing enables the integrated forming of complex microchannel structures such as biomimetic fractals, offering a new approach for high-heat-flux cooling. Targeting additive manufacturing, this paper adopts the CFD method to investigate the thermal-hydraulic performance of parallel straight channels, biomimetic leaf vein channels and spider-web channels. The effects of spacing ratio γ, heat flux q, and side number n on the flow and heat transfer of spider-web channels are analyzed emphatically. Parameters including average temperature Tave​, temperature uniformity k, Nusselt number Nu and pressure drop ΔP are obtained. The laws governing how structural parameters affect the overall heat transfer performance are revealed, providing a theoretical basis for the design of custom 3D-printed microchannel heat sinks.
The research results show that:
(1) As the Reynolds number Re increases, Tave​ decreases, k rises, and both Nu and ΔP increase for all three types of microchannels. At the same Re, the spider-web microchannel exhibits the lowest Tave​, highest k, largest Nu, and smallest ΔP, achieving the optimal overall performance. Its complex fractal network structure can be fabricated via additive manufacturing, showing great potential for engineering applications.
(2) Simulations of spider-web microchannels under different heat flux q demonstrate that an increase in q leads to a rise in Tave​ and a decline in k, while Nu and ΔP grow simultaneously. This indicates that convective heat transfer is enhanced but temperature uniformity deteriorates under high heat flux conditions. The findings can guide the design of additively manufactured heat sinks for chips under variable load conditions.
(3) Investigations into the spacing ratio γ reveal that a larger γ densifies the outer channels and sparsens the inner channels, increasing the heat transfer area. The minimum Tave​, maximum k and Nu, and minimum ΔP are achieved at γ=1.2. Considering additive manufacturing processes, γ=1.2 can be adopted as the starting point for optimization. Nevertheless, attention should be paid to powder residue and thermal deformation issues caused by excessively narrow channels.
(4) The study on side number n shows that the hexagonal configuration delivers the best heat transfer performance yet with relatively high ΔP. As the side number increases, the structure approaches a circular shape, accompanied by degraded heat transfer performance and reduced flow resistance. From the perspective of printability, the corners of hexagonal structures are self-supported and require no additional supports. In contrast, circular geometries contain overhanging regions that need support structures and pose challenges for post-processing. Therefore, the hexagon is the preferred configuration balancing heat transfer performance and manufacturability.

Biomimetic fractal microchannels,CFD numerical simulation,additive manufacturing,Spider-web structure,Heat transfer enhancement