Mechanism of high velocity jet formation after a gas bubble collapse near the micro fiber immersed in a liquid

Numerical simulations of the vapor bubble collapse near the micro fiber immersed in a subcooled liquid allow us to propose the mechanism of formation of high velocity liquid jet previously observed in experiments. It is shown that spherical symmetry breaking of the velocity field near the fiber creates axisymmetric radially converged water flow resulting in appearance of the cumulative jet. Numerical simulations demonstrate that physical mechanism of jet formation is mainly determined by bubble surface dynamic and is irrespective to the processes driving bubble shrinking. Dependency of the jet velocity on time as well as effect of fiber thickness and initial vapor bubble radius on jet intensity are studied. It is found that optimal fiber thickness at which the jet is the most powerful exists. This optimal value is not universal but depends on initial vapor bubble radius. (C) 2020 Elsevier Ltd. All rights reserved.