Formation and Breakup of an Immiscible Compound Jet with Density or Viscosity Stratification

Formation of compound drops by breakup of an axisymmetric compound jet injected from a coaxial nozzle into another immiscible coflowing fluid, at various density and viscosity ratios, is numerically investigated. The fluids are assumed to be Newtonian and incompressible and gravity is neglected for simplicity. A Finite Difference Method with Front Tracking is used to track the evolution and breakup of the compound jet. The outcomes of our numerical results show how density and viscosity ratios affect the compound jet's transition from dripping to jetting mode. The density ratios of inner-to-outer and intermediate-to-outer fluids affect compound jet breakup length, drop diameter and drop formation time more than comparable viscosity ratios. At high density and viscosity ratios, due to high inertia and viscous force respectively, the drop formation is more chaotic and mostly multi-core drops are formed.