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The stable conformation of a liquid-water drop on a horizontal cylindrical wire is studied. The stable conformation is established with various wire diameters. For each conformation of the drop the surface free energy is calculated using FEM simulation. The free energy for different drop shapes are compared with consideration to different volumes and contact angles. The effect of gravity on droplet shape with respect to wire diameter and droplet volume is observed. The droplet configurations under the influence of gravity and in the absence of gravity are observed and the shapes are described through coordinates of liquid-air and liquid-solid interfaces. The compensation of one interfacial energy with that of another is found. The wetting behaviour of liquid-drop on a wire is found to be significantly different from that on a plane surface under the influence of wire geometry. The numerical model was established taking liquid density at 1000kg/m3 and gravitational acceleration at 9.8 m/s 2. The numerical study is important in understanding the spreading of liquid droplets over cylindrical surfaces .The spreading of liquid over surfaces has got wide application in food industry, micro fluidics and more and in understanding the coating behaviour, liquid-solid and liquid-vapour interactions, material properties, etc.

Ethanol is recognized as one of the finest alternative bio-fuels due to its natural characteristics. Fundamental studies on ethanol droplet evaporation process are mainly either in stagnant environment or using some semi-empirical co-relations. Here, a fully numerical model based on the first principle is solved to investigate the effects of various atmospheric gases (Ar, N2, O2 and CO2) on droplet evaporation phenomenon under force convective situation. Two-dimensional governing equations of species, momentum and energy transfer of spherical coordinate system are solved, and the simulation is validated quantitatively with the literature. Uniform convective strength (Re = 100) is maintained for all cases examined at T∞ = 500K and P∞ = 0.1MPa. From the simulation results, it is observed that the viscosity ratio (liquid to gas) has effect on droplet life time. The ethanol droplet life time increases in less viscous atmospheric gases. The ethanol droplet life time is shorter in Ar gas, but heat-up period, wet-bulb temperature, and the surface blowing effect are higher in Ar compared to other atmospheric gases. The heat-up periods of the ethanol droplet in Ar, CO2, N2 and O2 atmosphere occupy around 30%, 20%, 17% and 16.5% of the total life time of the droplet, respectively. It is also noticed that, the heat-up period increases with increase in the thermal conductivity ratio (liquid to gas) and vice versa. Furthermore, the flow pattern of both gas- and liquid-phase in terms of streamline and the internal temperature distributions of the droplet are visualized at various time instants.

Studies on the evaporation phenomenon of a pure ethanol droplet have been mostly confined to the semianalytical modeling in stagnant ambient. Investigation into this aspect in a convective environment by considering the Navier–Stokes equation is also minimal. Hence, in this study we analyze and investigate the evaporation characteristics of a single‐component spherical‐shaped isolated pure ethanol droplet under force convective air environment by considering both gas‐ and liquid‐phase motions, nonunitary Lewis number in the interface, variable Stefan flow (blowing) effect, and the transient droplet heating. The finite difference method is utilized while solving the governing equations of the spherical polar coordinate system for species, momentum, and energy transfer. The maximum Reynolds number and ambient temperature are kept at 100 and 600 K, respectively. The present work is validated by comparing the normalized surface regression curve of the droplet with the earlier experimental and theoretical results. Using the current simulated data, flow and temperature profiles of both gas and liquid regions are visualized in streamline and isotherm contour plots at various instants of time. It is observed that at a moderate Reynolds number a detached vortex forms at the downstream location of the droplet. However, the detachment length increases with time. The temperature gradients along the droplet surface are observed at the initial stage. Moreover, the heat‐up period occupies about 20% of the total lifetime of the droplet. The droplet life and heat‐up period decrease with an increase in free‐stream velocity. In addition, the saturation temperature increases with ambient temperature.