Empirical Exploration of Thermal Transport due to Jet Impingement at Superhydrophobic Surfaces*

We present an empirical exploration of thermal transport due to jet impingement at heated smooth hydrophobic and post-patterned superhydrophobic surfaces. Post patterns with microfeature pitch (w = 8, 16, and 24 µm) and cavity fraction (F_c = 0.56 and 0.85) are explored. Further, the jet Reynolds number varies from 1.1 × 10⁴ to 1.7 × 10⁴ and surface heat flux varies from 2.5 × 10⁴ to 4.9 × 10⁴ W/m². Experimental results obtained from surfaces with smaller pitch and cavity fraction display a significant decrease in Nusselt number and agree well with predictions by an analytical model. Surfaces with larger pitch and cavity fraction yield a decrease in the Nusselt number, which is less than that predicted by the model. We propose that this phenomenon occurs due to dynamic wetting of the microcavities.