Bloodstain pattern analysis is a technique used in crime-scene reconstruction to determine the point of origin of a blood droplet as well as the method of its creation, e.g., dripping, wiping, or low-to-highspeed impact caused by anything from blunt trauma to cast-off to gunshot wounds. The primary problem of interest in this analysis is to determine of the initial size, speed, and impact angle...

There have been relatively few studies of turbulent collision rate of sedimenting droplets in the context of cloud physics, for which both the gravitational settling and inertial effects must be simultaneously considered. In this study, direct numerical simulations (DNS) were used to study the geometric collision rates of cloud droplets. Both Stokes drag law and a nonlinear drag law were consid...

In this paper we consider a free boundary problem which is used to describe the motion of contact lines of a liquid droplet on a flat surface. The elliptic nature of the equation for droplet shape and the monotonic dependence of contact line velocity on contact angle allows us to introduce a notion of “viscosity” solutions for this problem. Unlike similar free boundary problems, a comparison pr...

A simple experimental setup to study the impact and coalescence of deposited droplets is described. Droplet impact and coalescence have been investigated by high-speed particle image velocimetry. Velocity fields near the liquid-substrate interface have been observed for the impact and coalescence of 2.4 mm diameter droplets of glycerol∕water striking a flat transparent substrate in air. The exp...

A computational heat and mass transfer model of ceramic precursor solution containing droplets injected into a combustion flame is presented. Upon heat-up and vaporization, the precursor in droplets precipitate and ultimately form the ceramic material. Temperature and solute concentration distributions were computed to estimate the precipitation zones within droplets based on a simple homogeneo...

Flow characteristics and heat transfer of a water droplets laden flow behind a backward-facing step have been experimentally and numerically investigated for the condition of isothermally heated dry wall. Two sizes of step heights were employed corresponding to ReH = 5.3x103, 1.1x104. Water droplets of about 60 μm in mean diameter and small fine mist of less than 1 mm as a tracer of air flow we...

Determining the distributions of size and velocity of droplets formed at the end of primary breakup region is followed in this paper. The droplet formation stage at the end of primary breakup is random and stochastic and it can be modeled by statistical means based on the maximum entropy principle (MEP). The MEP formulation predicts the atomization process while satisfying constraint equations ...

The shape of microscopic fuel droplets may differ from the perfect sphere, affecting their external surface area and thus the heat transfer with the surrounding gas. Hence there is a need for the characterization of droplet shapes, and the estimation of external surface area, in order to enable the development of physically accurate mathematical models for the heating and evaporation of diesel ...

A water droplet in contact with a platinum surface was simulated by the molecular dynamics method. Water molecules were modeled with the well-known SPC/E model and the platinum surface was represented by three layers of harmonic molecules. The phantom molecules were used beneath the layers of platinum surface in order to mimic the constant temperature heat bath. As the potential function betwee...

Oxygen transport resistance at the air flow channel and gas diffusion layer (GDL) interface is needed in modelling the performance of a proton exchange membrane fuel cell (PEMFC). This resistance is expressed through the non-dimensional Sherwood number (Sh). The effect of the presence of a droplet on Sh is studied numerically in an isolated air flow channel using a commercially available packag...