High-speed visualization of the bubble dynamics on copper tubes

High-speed visualization of the bubble dynamics. Four copper tubes were used: a) Sample 1 (Ra = 0.032 µm), (b) Sample 2 (Ra = 0.108 µm), (c) Sample 3 (Ra = 0.544 µm), and (d) Sample 4 (surface: Ra = 0.544 µm + hexagonal hydrophobic patterns: Ra = 0.318 µm). Second heat flux interval (~ 30 kW/m2) & fourth heat flux interval (~ 450 kW/m2). For visualization of the four samples during the second heat flux interval (see supplementary movie 1) and the fourth heat flux interval (see supplementary movie 2).