Laser-induced surface tension alteration in liquids - Further investigations

High-intensity, short-pulse laser radiation incident on the free surface of an absorbing liquid results in heating that can alter the liquid surface tension, causing Marangoni convection. This flow can dominate the transport of thermal energy in the liquid. In previous work, the authors investigated laser-induced surface-tension-driven (LISTD) flows experimentally and analytically. A simple model based on a scaling analysis of the governing equations was performed that provided a reasonably good estimate of the measured flow associated with LISTD flows at low intensities and large beam areas. This work expands upon the previous work by performing a numerical simulation of the governing equations to obtain a more accurate description of the flow and heating associated with LISTD flows. The transport equations are solved using the SIMPLEC algorithm. The dependence on beam size and temperature increase in the liquid are investigated, with good agreement found between the numerical simulations and experimental data obtained in the previous study. The importance of natural convection and thermal conduction on the fluid-thermal transport were assessed numerically, with both found to be negligible for this liquid-laser system. Velocity and temperature profiles at the liquid surface are also presented, and it is observed that the temperature distribution and surface velocity rapidly decay after the laser pulse arrives.