Drop Interactions in Transient Flows with Applications to Liquid Sprays

The behavior of isolated drops, and binary and ternary systems of drops moving in tandem, in decelerating flows are numerically studied employing a finite-volume interface-tracking numerical scheme and a lattice-Boltzmann method for two-phase flows. The influence of Weber and Ohnesorge numbers, separation distance between drops, and drop size-ratio on the transient deformation and breakup of the drops are discussed. Drag coefficients for the drops are also reported. It is shown that in binary drops, the trailing drop decelerates slower than the leading one and breaks up slower. Both drops decelerate slower than the isolated drop. In the case of ternary drops, the three drops decelerate slower than the isolated one. The leading drop breaks up fastest followed by the middle one. The drag coefficients are transient and vary significantly from those of spheres in transient flows as a result of drop deformation.