Mechanism of collision and drainage of liquid droplet around sphere placed within a hollow cylinder

Abstract

It is attempted earnestly to elucidate the mechanism of collision and drainage of liquid mass around the spherical substrate suspended within the hollow cylinder using Gerris open-source code by employing Volume of Fluid (VOF) methodology. Various influencing parameters, namely, sphere-to-droplet diameter ratio (Ds/Do), Weber number(We), Ohnesorge number (Oh), and Bond number(Bo) are employed to observe the drainage mechanism through the constricted path. The pattern of the interfacial morphology of droplet collision and drainage mechanism is presented using numerical contours. It is important to mention herein that the droplet undergoes several important stages like collision, cap formation, engulfment, drainage, and pinch-off. The passage between the sphere and the cylinder is sufficiently wider at a lower value of Ds/Do due to which the liquid mass is drained out completely without any hindrance. The drainage process becomes considerably faster at a higher We compared to a lower We. In addition, the flow of liquid mass through the passage gets delayed at a greater Oh than a lower Oh assuming a given value of We and Ds/Do. The liquid drop requires less time to pass through the constricted path at lower Bo for a given value of Ds/Do and We. We have also attempted to quantify the drainage of liquid volume passes through the passage, which is denoted as (Q*=Q/Qo). One can notice the increasing pattern of Q/Qo with continuous progress of time stamp for all cases of Ds/Do for a fixed value of We.