Numerical simulation of axisymmetric drop formation using a coupled level set and volume of fluid method

Numerical simulations have been carried out to examine the axisymmetric formation of drops of Newtonian liquid injected from a vertical orifice under constant flow conditions into the ambient air. The numerical simulation was performed by solving axisymmetric Navier-Stokes equations with a coupled level-set and volume-of-fluid (CLSVOF) method. In this work, the dynamics of the formation of drops are investigated over a range of the Ohnesorge number Oh=0.01,0.023 and 0.13, and the Bond number Bo=0.33,0.5 and 2.205, as the Weber number We increases. The different responses of drop formation such as period-1 dripping with (P1S) or without satellite drops (P1), complex dripping (CD) and jetting (J) are discussed. The different responses of drop formation were identified quantitatively from the time history of growing length of drop at the orifice. The transition of different responses is shown on the map which exhibits the variation of limiting length of drop at breakup or the volume of the detached primary drop with We while keeping Oh and Bo fixed. The numerical investigation of liquid jet formation in terms of the evolution of growing length of jet under different computational grid sizes was discussed. It is proposed that the almost stable liquid jet formation can be found as the mesh size decreases. The accuracy of the present computed results is assessed by comparisons with the previous investigations. Furthermore, it is shown that at high Bo=2.205, low Oh=0.023 and We=0.0177, the system exhibits period-2 with satellite drop (P2S) response which was not reported before in literature.