Deformation and Breakup of Drops in Axisymmetric Flows and Comparisons with the Taylor Analogy Breakup Model

The Taylor analogy breakup (TAB) model is used for the prediction of drop deformation and drop breakup in spray simulations conducted with CFD codes. This model assumes that a spherical droplet moving in a gas stream behaves like a forced, damped harmonic oscillator in which the forcing term is given by the aerodynamic drag, the damping is due to the liquid viscosity and the restoring force is supplied by the surface tension. The deformation equation is given in terms of the normalized drop deformation, and it is assumed that the droplet breaks up if this deformation exceeds a critical value. In this study, CFD methods are used to determine the conditions under which the TAB model is valid and develop a modified TAB model which predicts the deformation more accurately. A full 3D simulation is performed to justify the axisymmetric assumption. In order to keep the drop within the fixed computational domain, the location of the drop is adjusted in almost every time step. The results are compared with the TAB and the modified TAB models, including the critical deformation at which the drop starts disintegrating and the oscillation period. The results show good agreement with the modified TAB model. Further, the types of breakup are found to be in good agreement with experimental observations.