Alexander L. Yarin 교수

The review deals with drop impacts on thin liquid layers and dry surfaces. The impacts resulting in crown formation are referred to as splashing. Crowns and their propagation are discussed in detail, as well as some additional kindred, albeit nonsplashing, phenomena like drop spreading and deposition, receding (recoil), jetting, fingering, and rebound. The review begins with an explanation of various practical motivations feeding the interest in the fascinating phenomena of drop impact, and the

A localized approximation was developed to calculate the bending electric force acting on an electrified polymer jet, which is a key element of the electrospinning process for manufacturing of nanofibers. Using this force, a far reaching analogy between the electrically driven bending instability and the aerodynamically driven instability was established. Continuous, quasi-one-dimensional, partial differential equations were derived and used to predict the growth rate of small electrically drive

The impact of drops impinging one by one on a solid surface is studied experimentally and theoretically. The impact process is observed by means of a charge-coupled-device camera, its pictures processed by computer. Low-velocity impact results in spreading and in propagation of capillary waves, whereas at higher velocities splashing (i.e. the emergence of a cloud of small secondary droplets, absent in the former case) sets in. Capillary waves are studied in some detail in separate experiments. T

Sessile and pendant droplets of polymer solutions acquire stable shapes when they are electrically charged by applying an electrical potential difference between the droplet and a flat plate, if the potential is not too large. These stable shapes result only from equilibrium of the electric forces and surface tension in the cases of inviscid, Newtonian, and viscoelastic liquids. In liquids with a nonrelaxing elastic force, that force also affects the shapes. It is widely assumed that when the cr

Abstract The mini‐review is devoted to coaxial electrospinning (co‐electrospinning, emulsion electrospinning), a group of novel methods for making core–shell nanofibers and hollow nanotubes. The physical aspects of the process are described in brief, in particular, its modeling and possible drawbacks of the process resulting in formation of fibers without a long intact core. After that the main applications of co‐electrospinning are considered. They include drug release, encapsulation of differe

Three-dimensional carbon fiber electrodes prepared by electrospinning and solution blowing are shown to be excellent electrode materials for bioelectrochemical systems such as microbial fuel cells or microbial electrolysis cells. The bioelectrocatalytic anode current density is shown to reach values of up to 30 A m−2, which represents the highest reported values for electroactive microbial biofilms.

The rate of heat and mass transfer at the surface of acoustically levitated pure liquid droplets is predicted theoretically for the case where an acoustic boundary layer appears near the droplet surface resulting in an acoustic streaming. The theory is based on the computation of the acoustic field and squeezed droplet shape by means of the boundary element method developed in Yarin, Pfaffenlehner & Tropea (1998). Given the acoustic field around the levitated droplet, the acoustic streaming

A comprehensive exposition of micro and nanofiber forming, this text provides a unified framework of all these processes (melt and solution blowing, electrospinning, and so on) and describes their foundations, development and applications. It provides an up-to-date, in-depth physical and mathematical treatment, and discusses a wide variety of applications in different fields, including nonwovens, energy, healthcare and the military. It further highlights the challenges and outstanding issues fro

This paper deals with the theoretical and experimental investigation of acoustically levitated droplets. A method of calculation of the acoustic radiation pressure based on the boundary element method (BEM) is presented. It is applied to predict shapes of droplets levitated in an acoustic field (and as a result, deformed by it). The method was compared with several known exact and approximate analytical results for rigid spheres and shown to be accurate (and a widely used approximate formula for

A comprehensive account of the physical foundations of collision and impact phenomena and their applications in a multitude of engineering disciplines. In-depth explanations are included to reveal the unifying features of collision phenomena in both liquids and solids, and to apply them to disciplines including theoretical and applied mechanics, physics and applied mathematics, materials science, aerospace, mechanical and chemical engineering, and terminal ballistics. Covering a range of example

Abstract This article reports a novel hybrid multiscale carbon‐fiber/epoxy composite reinforced with self‐healing core‐shell nanofibers at interfaces. The ultrathin self‐healing fibers were fabricated by means of coelectrospinning, in which liquid dicyclopentadiene (DCPD) as the healing agent was enwrapped into polyacrylonitrile (PAN) to form core‐shell DCPD/PAN nanofibers. These core‐shell nanofibers were incorporated at interfaces of neighboring carbon‐fiber fabrics prior to resin infusion and

Electrospinning of polymer nanofibers often begins with a single, straight, elongating, and electrified fluid jet that emanates from a droplet tip when the electric field at the surface is high enough. After some distance an electrically driven bending instability of the elongating jet occurs. For a polymer solution suitable for electrospinning, capillary instability does not cause the jet to become a spray of droplets. Under some conditions, a sequence of secondary jet branches emanates from th

In this article, we review recent work on the co-electrospinning of polymer core–shell nanofibers and the manufacture of hollow nanotubes. The encapsulation and release of bioactive compounds from co-electrospun core–shell fibers is considered next, bearing in mind such applications as sensors and drug release. Then, nanofluidic phenomena in nanotubes made via co-electrospinning (as well as via the other processes) are discussed. We also consider dielectrophoresis in microchannels as a possible