A dual grid level set method based study of interface-dynamics for a liquid jet injected upwards into another liquid

Dynamics and breakup of an axi-symmetric liquid jet injected upwards into another stationary or co-flowing immiscible liquid is investigated numerically. Simulations are done using an in-house code based on a novel DGLSM (dual grid level set method). Furthermore, a novel procedure - based upon physical interpretation of the various functions in Level Set Method - is demonstrated here as a powerful numerical tool to calculate certain parameters (diameter as well as frequency of drop formation and temporal variation of jet length at the axis), which characterize the unsteady interface-dynamics. Six different combination of the dispersed and continuous fluid are subjected to various injection velocity, resulting in a large variation in the non-dimensional governing parameters such as viscosity-ratio and Weber number. From the temporal variation of jet length and instantaneous interface, three drop formation regimes are proposed: Periodic Uniform Drop formation (P-UD), Quasi-Periodic Non-Uniform Drop formation (QP-NUD) and Chaotic Non-Uniform Drop formation (C-NUD); demarcated in a drop formation regime map for various Weber number and viscosity ratio. Their effect on the mean value of jet breakup length (Ld,m), detached drop diameter (Dd,m) and drop formation frequency (Stm) is also studied. After a more detailed study on stationary continuous fluid, the effect of co-flowing continuous fluid is studied; and is found to stabilize the drop formation regime and increase the frequency of drop formation.