Spray interface drag modeling based on the power-law droplet velocity using the moment theory

Interphase momentum exchange of a polydispersed two-phase flow is numerically studied by using a model based on interfacial drag effects of a bulk liquid, ligaments, and droplets entrained in the air flow. A power-law relation is proposed between the droplet velocity and its diameter. The dispersed phase is modeled using the methodology of spray moments of the drop size distribution. All the equations are solved in a Eulerian framework using the finite volume approach, and the phases are coupled with the source terms. The proposed dependence accurately simulates the droplet behavior because droplets with larger diameters experience a higher drag and generally have higher velocities than smaller droplets. The model shows reasonable agreement with experimental and numerical data on the spray tip penetration and Sauter mean radius.