Formation of oil drops discharged underwater

Abstract

The formation of oil droplets during the underwater discharge is investigated both experimentally and numerically. The focus is placed on the size of the drops formed with the variation of discharge speed and nozzle diameter in the experiment. In the numerical study, the Navier-Stokes equations for incompressible and Newtonian fluids are solved in axisymmetric cylindrical coordinates by the Front-Tracking/Finite Difference method, and we address the dynamics of jet and the drop shape for different Reynolds, Weber, and Froude numbers as well as viscosity ratios. The results show that the dynamics of jet formation and the breakup of the jet into drops depend on inertia, interfacial tension, buoyancy, and viscous forces. The capillary wave instability is observed at the higher inertia force, and the "end-pinching" plays an important role in the practical jet breakup as well as the capillary wave instability.