Direct ink writing (DIW) has demonstrated great potential as a multimaterial multifunctional fabrication method in areas as diverse as electronics, structural materials, tissue engineering, and soft robotics. During DIW, viscoelastic inks are extruded out of a 3D printer's nozzle as printed fibers, which are deposited into patterns when the nozzle moves. Hence, the resolution of printed fibers ...

Experiments on the onset of buoyant instabilities leading to periodic formation of vortical structures in planar buoyant plumes of helium and helium/air mixtures injected into quiescent air are reported for a range of nozzle widths (w520– 70 mm), plume fluid densities ~pure helium to that approaching air!, and velocities at the nozzle exit. First, the plume parameters corresponding to the onset...

the main purpose of this study is to introduce a new method for nanofibers by bulk layer production. in the present method the effect of some parameters including take-up velocity, applied voltage, polymer solution concentration on density of produced layers is investigated. the compression characteristic of nanofiber layers produced under optimum electrospinning is also investigated. it was sh...

Starting flow through a nozzle or orifice typically results in the transient formation of a leading vortex ring and trailing jet. Experiments are conducted to investigate the dynamics of this process in the case of a temporally variable nozzle exit diameter, with the aim of understanding these flows as they occur in Nature and emerging technologies. By kinematically decoupling the source flow f...

Particle beams have traditionally been produced by supersonic expansion of aparticle-ladengas through a single nozzle to vacuum. However, it has been shown that, by passing the particle-laden gas through a series of axi-symmetric subsonic contractions and expansions (an aerodynamic lens system) prior to the supersonic expansion to vacuum through a single nozzle, beam divergence can be signiŽ ca...

The discharge of grains from a hopper or silo has received considerable attention, both because it is relevant to numerous industries, and a model system for examining general features of granular flow [1, 2]. These studies have generally focused on the motion of grains inside the hopper and the flow rate of material out of the nozzle. It is known that these systems can exhibit intermittent jam...

Understanding and controlling mixing and combustion processes is fundamental in order to face the challenges set by the ever more demanding pollutant regulations and fuel consumption standards of direct injection diesel engines. The fundamentals of these processes haven been long studied by the diesel spray community from both experimental and numerical perspectives. However, certain topics, su...

Wicking flow inside capillary tubes can attain considerable momentum so as to produce a liquid jet at the end of the tube. Auto-ejection refers to the formation of droplets at the tip of such a jet. Experimental observations suggest that a tapering nozzle at the end of the capillary tube is necessary for auto-ejection; it has never been reported for a straight tube. Besides, most experimental r...

Stable drop jettability is mandatory for a successful, technical scale inkjet printing, and accordingly, this aspect has attracted much attention in fundamental and applied research. Previous studies were mainly focused on Newtonian fluids or polymer solutions. Here, we have investigated the drop jetting for zinc oxide (ZnO) particulate suspensions. Generally, the inverse Ohnesorge number Z = O...