Effect of surface roughness on thermofluidic characteristics of open-cell metallic foam: A pore-scale numerical study

To augment the thermal performance of open-cell metallic foams (MFs) in heat transfer applications, rough foams are envisioned by covering the ligament surfaces with micro-rods. A pore-scale three-dimensional (3D) numerical model is developed to evaluate their transport characteristics under various Reynolds numbers (25 to 225) and compare them with traditional smooth foams. The simulation results, validated by experimental measurements, demonstrate that rough foams achieve a 60.08% to 104.28% increase in heat transfer efficiency due to increased specific surface area and intensified flow disturbance caused by the micro-rods. However, the addition of micro-rods also increases pressure drop due to impeding flow, expanding low-pressure areas, and generating local eddies. Despite these drawbacks, rough foams still demonstrate superior comprehensive thermal efficiency, with an average improvement of 44.47% to 82.90% under iso-pumping conditions. Therefore, tailoring the microstructure of MFs can provide new insights for optimizing compact heat exchangers in thermal management of high-power electronics.