Evaporation Rate of Distilled Water Drop on the Surface of Non-Ferrous Metals

We studied experimentally the evaporation process of distilled water drops on the surfaces of non-ferrous metals. Investigations were conducted on the experimental setup using a shadow optical system. The main elements of this system are the source of plane-parallel light and photographic camera. According to the contact diameter change during the evaporation, three stages have been determined (spreading, pinning, depinning). It has been found, that the dependence of evaporation rate on drop volume at low temperatures appear to be well fit by a power function

Wicking and evaporation of liquids in porous wicks: a simple analytical approach to optimization of wick design

Wicking and evaporation of volatile liquids in porous, cylindrical wicks is investigated where the goal is to model, using simple analytical expressions, the effects of variation in geometrical parameters of a wick, such as porosity, height and bead-size, on the wicking and evaporation processes, and find optimum design conditions. An analytical sharp-front flow model involving the single-phase Darcy’s law is combined with analytical expressions for the capillary suction pressure and wick permeability to yield a novel analytical approach for optimizing wick parameters. First, the optimum beadradius and porosity maximizing the wicking flow-rate are estimated. Later, after combining the wicking model with evaporation from the wick-top, the allowable ranges of bead-radius, height and porosity for ensuring full saturation of the wick are calculated. The analytical results are demonstrated using some highly volatile alkanes in a polycarbonate sintered wick

Snap evaporation of droplets on smooth topographies

Droplet evaporation on solid surfaces is important in many applications including printing, micro-patterning and cooling. While seemingly simple, the configuration of evaporating droplets on solids is difficult to predict and control. This is because evaporation typically proceeds as a “stick-slip” sequence—a combination of pinning and de-pinning events dominated by static friction or “pinning”, caused by microscopic surface roughness. Here we show how smooth, pinning-free, solid surfaces of non-planar topography promote a different process called snap evaporation. During snap evaporation a droplet follows a reproducible sequence of configurations, consisting of a quasi-static phase-change controlled by mass diffusion interrupted by out-of-equilibrium snaps. Snaps are triggered by bifurcations of the equilibrium droplet shape mediated by the underlying non-planar solid. Because the evolution of droplets during snap evaporation is controlled by a smooth topography, and not by surface roughness, our ideas can inspire programmable surfaces that manage liquids in heat- and mass-transfer applications

Devising music: applying creative approaches from dance and theatre to music composition

My principal research question is: How can the directed devising techniques and principles of practice found in contemporary dance and theatre be adapted to the composition of music? The relationship between fixed material and improvisation within devised projects is often a grey area (see Etchells: 2013b). Some performances are tightly scored with little room for the performers to steer the performances - whereas other performances could be almost seen as free improvisation. The difference between improvisation and devising is always found in the performer’s relationship to the material. Devising processes can generate material whose definition is so elusive that its realisations vary wildly from night to night. But however inexpressible, devising material always has a definite meaning for the performers to which they return in every performance - seeking to generate new interactions and new connections. In every performance we search to find the ephemeral moments that might become a lasting memory. During my research, I have become increasingly interested in developing a performance practice that uses performer freedom to discover and stimulate unique experiences within performances. Although I feel I have made progress in moving towards this, I know that there is much more to explore in this practice. All submitted works and examples are available online at: doctorate.michaelpicknett.co

Transport and deposition patterns in drying sessile droplets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106826/1/aic14338.pd

Experimental study of water evaporation of sessile droplets on a solid substrate with different thermal conductivities

The results of experimental studies of water evaporation of sessile droplet on solid substrates with different thermal conductivities are presented. In experiments during droplet evaporation the temperature of its surface was determined using the infrared thermography method. The obtained results showed that interfacial temperature was higher than the adiabatic evaporation temperature for all substrates. As thermal conductivity of the substrate decreased, the droplet temperature decreased and the evaporation lifetime increased significantly. As a result it was established that the thermal conductivity of the material has a significant effect on the evaporation of droplets

Dynamics and universal scaling law in geometrically-controlled sessile drop evaporation

The evaporation of a liquid drop on a solid substrate is a remarkably common phenomenon. Yet, the complexity of the underlying mechanisms has constrained previous studies to sphericallysymmetric configurations. Here we investigate well-defined, non-spherical evaporating drops of pure liquids and binary mixtures. We deduce a universal scaling law for the evaporation rate valid for any shape and demonstrate that more curved regions lead to preferential localized depositions in particle-laden drops. Furthermore, geometry induces well-defined flow structures within the drop that change according to the driving mechanism. In the case of binary mixtures, geometry dictates the spatial segregation of the more volatile component as it is depleted. Our results suggest that the drop geometry can be exploited to prescribe the particle deposition and evaporative dynamics of pure drops and the mixing characteristics of multicomponent drops, which may be of interest to a wide range of industrial and scientific applications