Direct visualization of temperature evolution of interfacial cavitation

Cavitation at the air/water interface, unlike the bulk cavitation embedded inside liquids, is produced by CO₂ laser impacting on water. By using thermal camera, direct visualization of temperature evolution of interfacial cavitation is achieved. Gaussian distribution is observed when none cavitation occurs due to the Gaussian distribution of laser intensity, while an interesting ring-shape distribution is observed with cavitation formation. Theoretically, we attribute the ring-shape temperature distribution to the coupling of heat transfer and liquid outflow driven by cavitation expansion at large Peclet number (Pe~10³) associated with the dominate convection. This novel temperature profiles is validated by our numerical simulation for the cavitation formation and heat transfer. Moreover, we identify that superheating is required for interfacial cavitation, and propose a classical nucleation model consistent with experiments excellently. These results might have implications in microfluidic manipulation, nanomaterial synthesis and medical treatment.