On a three-dimensional volume tracking model of droplet impact

Abstract

A three-dimensional model has been developed, of droplet impact onto asymmetric surface geometries. The model is based on RIPPLE, and combines a xed-grid control volume discretization of the ow equations with a volume tracking algorithm to track the droplet free surface. Surface tension is modelled as a volume force acting on uid near the free surface. Contact angles are applied as a boundary condition at the contact line. The results of two scenarios are presented, of the oblique impact of a 2 mm water droplet at 1 m s ont o a 4 5 o incline, and of a similar impact of a droplet onto a sharp edge. Photographs are presented of such impacts, against which the numerical results are compared. The contact angle boundary condition is applied in one of two ways. For the impact onto an incline, the temporal variation of contact angles at the leading and trailing edges of the droplet was measured from photographs. This data is applied as a boundary condition to the simulation, and an interpolation scheme proposed to evaluate contact angles between the leading and trailing edges. A simpler model is then proposed, for contact angle as a function of contact line velocity, and applied to both geometries. The model requires values of only two contact angles, at a rapidly advancing and a rapidly receding contact line. Simulation results compare well with photographic data.

Formation of Solid Splats During Thermal Spray Deposition

“…Droplets may land at an incline to the substrate, interact with previously deposited splats, or the liquid-solid contact may become unstable and wavy. 90,91). The influence of the surrounding gas was neglected in the model, the liquid assumed incompressible and fluid flow modeled as being Newtonian and laminar.…”

A mesh-dependent model for applying dynamic contact angles to VOF simulations

“…On the other hand, most VOF implementations (and more generally, most interface capturing techniques) utilize cell face normal velocities to advect volume fractions (e.g. [21][22][23]). This implies that the methodology includes an ''implicit" (or ''effective") slip length at no-slip boundaries.…”

Comparison of measured and modelled droplet–hot wall interactions

“…However, in their study, the viscosity and the surface tension forces in the momentum conservation equations were ignored. A volume-tracking methodology was used by Bussman et al [9] and Bussman et al [10]. They developed a three-dimensional model based on the RIPPLE code (Kothe and Mjolsness [11]) to simulate the droplet collision and splash on an inclined surface.…”