Towards understanding of spreading and detachment during droplet impact onto a hemispherical surface

Abstract

A computational study has been carried out to characterize the morphological and hydrodynamic behavior of water droplets during the impingement onto the hemispherical substrate. Volume of fluid (VOF) methodology is employed to carry out the simulations. Various essential and interesting stages, such as free falling, impact, cap formation, encapsulation, uncovering, oscillation, and detachment are encountered during entire impact cycle. The effects of various parameters are hemisphere-to-droplet diameter ratio (Dh/Do), contact angle (θ), Bond number (Bo), Ohnesorge number (Oh), and release height (h/Do) on deformation factor (ξ) of the droplet is delineated thoroughly. Droplet fails to detach from the target at higher Oh and greater Dh/Do. Based on this, a scatter regime plot has been represented to distinguish between two different hydrodynamic behavior of droplets. A correlation is developed to estimate the maximal deformation factors in terms of Dh/Do, Bo, Oh, θ, and h/Do and it performs extremely well within ±3.5% of the computational data.