CONICET | Buscador de Institutos y Recursos Humanos

Secondary break-up consist on the decomposition of droplets, ligaments and rims into smallerdroplets forming a spray. This phenomenon is driven by interface deformation given by the growth of hy-drodynamic instabilities, depending on Reynolds and Weber numbers. Bag mode break-up takes place atmoderate gas Weber numbers, at which the drops turns into a film and inflates. Film thickness decreasesuntil a hole forms and expands, giving place to decomposition in smaller droplets. This mechanism ispresent in several break-up processes and is of great interest to understand the underlying physics ofliquid atomization. In this work, we present the Direct Numerical Simulations (DNS) results of a singleliquid droplet submerged in an air stream in bag mode regime. Navier-Stokes equations for the two-phaseflow are solved using a Volume of Fluid with a Piecewise Linear Interface Capturing (PLIC) formulationand geometrical advection schemes on the volume fraction and momentum equations, programmed inthe Basilisk suite. The deformation of the drop into a film and the posterior evolution of its thickness isstudied until the formation of a hole and the results are compared with experimental data.