Liquid resistance in underwater laser propulsion

To investigate liquid resistance in underwater laser propulsion, we conducted underwater propulsion experiments with cylindrical titanium targets of identical mass but varying propulsion areas through high-speed photography. An analytical formula was derived to elucidate the relationship among the kinetic energy of the target, the energy of the bubble induced on the target's propulsion surface, and the energy loss due to liquid resistance. The results indicate that during the process of underwater laser propulsion, the liquid resistance experienced by the target before achieving a stable velocity is directly proportional to both its velocity and the area of its propulsion surface.