A numerical study of pendant drop formation from a capillary tube.

摘要

Numerical simulations leave been performed to investigate the breakup mechanism of liquid droplet formation from a capillary tube under the influence of gravity. The full transient Navier-Stokes equation is solved in a two-dimensional axi-symmetrical coordinate system. The algorithm for the volume tracking method is the Volume of Fluid (VOF) method and the free surface interface is reconstructed by the Piecewise Linear Interface Calculation (PLIC) scheme. Surface force is estimated by the Continuum Surface Force (CSF) model and a new algorithm incorporated in the computer code, the Coupled Level Set Volume of Fluid (CLSVOF) scheme, has been used along with the former scheme, the VOF-PLIC. The accuracy of the numerical models has been validated by comparing with available experimental and numerical results. The breakup phenomenon is investigated and its mechanism has been theoretically identified. Parametric studies have been done on the effect of the inlet velocity profile, viscosity, gravity, and surface tension coefficient. The results are in reasonable agreement with experimental measurement.