Transient deformation and breakup of a droplet in confined shear flow

In many industrial applications, droplets generally move in complex external flow environment with velocity gradient and wall confinement. Thus the differences in the deformation drag properties and breakup of an accelerating droplet moving in uniform flow versus in confined shear flow are different; these are studied in this paper. Under the axisymmetric assumption, the incompressible Navier-Stokes equations coupled with the Volume of Fluid model are solved. It is found that the larger confinement ratio results in smaller radial deformation but larger axial deformation of the drop and the critical Weber number for breakup in confined shear flow is smaller than that in uniform flow. The radial breakup mode is observed in uniform flow, while the axial breakup mode is found in the confined shear flow. The separated gas flow wake region behind the droplet becomes smaller and even disappears completely with the increasing confinement ratio.