Measurements of cloud condensation nuclei (CCN) concentrations (cm−3) at five levels of supersaturation between 0.2–1%, together with remote sensing profiling and aerosol size distributions, were performed at an urban background site of Athens during the Hygroscopic Aerosols to Cloud Droplets (HygrA-CD) campaign. The site is affected by local emissions and long-range transport, as portrayed by ...

The surface tension gradients in the front and rear sides of a 1-hexanol droplet exhibiting self-propelled motion were compared by a time-resolved quasi-elastic laser scattering method. The velocity of the alcohol droplet strongly correlated to the difference of the inverse of the recovery distances of the surface tensions between the front and rear sides. This result indicates that the spontan...

An analytical model is presented for the deformation of an ellipsoidal Newtonian droplet, suspended in another Newtonian fluid with different viscosity and zero interfacial tension. The theory is exact for any linear velocity field, and is not limited to small deformations. It encompasses some well-known special cases, such as Jeffery’s equation for solid axisymmetric particles and Taylor’s sma...

We present the results of a combined experimental and theoretical investigation of oil droplets sliding on fibres. First, both the axisymmetric shape and the motion of a droplet on a vertical fibre are described. The motion is shown to result from a balance between the droplet weight and the viscous stresses. On a long-term range, the droplet loses some mass through coating the fibre, which dec...

A model is formulated to describe the dynamics of electro-wetting-induced transport of liquid droplets. The velocity of droplet transport as a function of actuation voltage is derived. The operating parameters include the viscosity of the droplet and the medium through which it actuates, contact-line friction, system geometry, and surface tension. Numerical coefficients are extracted from exper...

A mesoscale fluid film placed on a solid support may break up and form droplets. In addition, droplets may exhibit spontaneous translation by modifying the wetting properties of the substrate, resulting in asymmetry in the contact angles. We examine mechanisms for droplet formation and motion on uniform and terraced landscapes, i.e., composite substrates. The fluid film stability, droplet forma...

Droplet microfluidic techniques can perform large numbers of single molecule and cell reactions but often require controlled, periodic flow to merge, split, and sort droplets. Here, we describe a simple method to convert aperiodic flows into periodic ones. Using an oil extraction module, we efficiently remove oil from emulsions to readjust the droplet volume fraction, velocity, and packing, pro...

When a droplet hits a hot surface beyond the Leidenfrost temperature, the droplet will bounce on the hot surface. This unique bouncing phenomenon only occurs in the film boiling region. This paper discusses the relationship between the residence time of droplet and droplet bouncing phenomena during droplet impact on hot horizontal surfaces. In this experiment, aluminum (mirror polished) was sel...

The prediction of droplets diameter and velocity distribution in a spray is so difficult since its process and mechanism is not completely known and depends too many parameters. The early stage of the atomization process (Primary Breakup) is clearly deterministic, whereas the final stage of spray formation (Secondary Breakup) is random and stochastic. In the second region, which deals with the ...