We report highly reproducible gravimetric and optical measurements of microdroplets that lend insights into the fundamentals of drop-on-demand (DOD) printing. Baseline fluidic pressure within the DOD dispenser was controlled to within 0.02 hPa, enabling long-term stability in dispensed droplet mass with observed variations near 1% (RSD) for isobutanol. The gravimetric measurements were sensitiv...

We report on a dramatic order-of-magnitude increase in flow velocity within pinned evaporating droplets toward the end of their lifetime. The measurements were performed using high-speed microparticle image velocimetry. The study revealed interesting observations about the spatial and temporal evolution of the velocity field. The profile along the radius of the droplet is found to exhibit a max...

[1] Using large-eddy simulations (LESs) of six observed boundary layer cases as benchmark data sets, we diagnosed vertical velocity as the sum of the grid-mean (w) and the subgrid-scale w using an empirical method we have developed. We have found that the subgrid-scale w is best characterized by the root-mean square of w02. The vertical velocity is expressed in the form of w = w + c ffiffiffiff...

The velocity of a molecule evaporated from a mass-selected protonated water nanodroplet is measured by velocity map imaging in combination with a recently developed mass spectrometry technique. The measured velocity distributions allow probing statistical energy redistribution in ultimately small water nanodroplets after ultrafast electronic excitation. As the droplet size increases, the veloci...

Introduction: The data of chondrule shapes is a strong clue for elucidating the chondrule formation mechanism. Recently, the three-dimensional data of chondrule shapes has been measured by the X-ray microtomography [1]. The external shapes were approximated as three-axial ellipsoids with a-, band nd c-axes (axial radii are A, B, and C (A≥B≥C), respectively). The plot of C/B vs. B/A shows that t...

Molecular dynamics simulations are used to investigate the subcritical and supercritical evaporation of a Lennard-Jones (LJ) argon nanodroplet in its own vapor. Using a new technique to control both the ambient temperature and pressure, a range of conditions are considered to define a transition line between subcritical and supercritical evaporation. The evaporation is considered to be supercri...

The freezing of freely suspended supercooled water droplets with a diameter of bigger than a few micrometers splits into two rather different freezing stages. Within the first very fast dendritic freezing stage a spongy network ice with an ice portion of less than one-third forms and more than two-thirds of liquid water remain. In the present work the distribution of the ice portion in the drop...

A computer-aided analysis system has been developed in this study to simulate the formation, ejection, and impact of liquid droplet in a piezoelectric inkjet printing device. The effects of voltage pulse of the piezoelectric actuator and surface tension of the liquid on the droplet ejection phenomena are evaluated by the simulation system. The droplet ejection is a fluid flow phenomenon, which ...

A numerical investigation of unsteady liquid fuel droplet combustion with droplet heating and internal circulation under forced convection is presented. The droplet is burning within an airstream at atmospheric pressure and under zero-gravity conditions. Combustion is modeled using finite rate kinetics and a one-step overall reaction. The numerical model includes a new multicomponent formulatio...

We examine the evolution of an Ising ferromagnet endowed with zero-temperature single spin-flip dynamics. A large droplet of one phase in the sea of the opposite phase eventually disappears. An interesting behavior occurs in the intermediate regime when the droplet is still very large compared to the lattice spacing, but already very small compared to the initial size. In this regime the shape ...