The dynamic aspects of droplet impingement on a porous ceramic surface were studied experimentally. Single-shot flash photography was used to photographically record the deformation and spreading on the surface. The observations were made with ambient pressure (0.10 MPa), ambient temperature (cu. 22”C), initial droplet diameter (1.5 mm), and the impact Weber number (43) fixed. The primary param...

The increasing demand for high energy density fuels and the concern for their safety have propelled research in the field of gelled propellants, where understanding the combustion of single gelled fuel droplets is the first stage to predict the spray combustion characteristics. The experiments utilized single-isolated freely falling gelled unsymmetrical dimethylhydrazine (UDMH) droplets instead...

We experimentally study the shear flow of oil-in-water emulsion droplets in a thin sample chamber with a hopper shape. In this thin chamber, the droplets are quasi-2D in shape. The sample is at an area fraction above jamming and forced to flow with a constant flux rate. Stresses applied to a droplet from its neighbors deform the droplet outline, and this deformation is quantified to provide an ...

Methods for implementing variable surface tension on two popular Lattice– Boltzmann models, the original gradient-based chromodynamic model, and the Shan–Chen model, are explored and examined. The experiment, inspired by the work of Greenspan, consists of reducing the surface tension at two poles of a circular droplet due to a diffusive solute (surfactant). Both Lattice Boltzmann models are abl...

The short review presents the analysis of the consecutive evolution of the rheology of emulsions starting from dilute systems (behavior of an individual liquid droplet in a continuous liquid phase) till the highly concentrated emulsions, in which droplets loose their spherical shape and become polygons. Along with the increase of the internal phase concentration, this is the transition from a s...

The energy budget and dissipation mechanisms during droplet impact on solid surfaces are studied numerically and theoretically. We find that for high impact velocities and negligible surface friction at the solid surface (i.e. free-slip), about one half of the initial kinetic energy is transformed into surface energy, independent of the impact parameters and the detailed energy loss mechanism(s...

Liquid-film contact lines driven over a surface (substrate) by gravity, centrifugal force, Marangoni force, or wind, exhibit a wealth of instabilities that control many coating and cleaning processes. Starting from a sheet with an approximately straight contact line advancing over the substrate, these instabilities lead to fingering of the sheet to form rivulets, meandering and oscillation of t...