arXiv subjects

Suhas Tamvada

Publications and source records attributed to Suhas Tamvada.

3 recordsLinked to original sources

arXiv2025

Increased solidification delays fragmentation and suppresses rebound of impacting drops

The splat formed after drop impact on supercooled solid surfaces sticks to it. On the contrary, a sublimating supercooled surface such as dry ice inhibits pinning and therefore efficiently rebounds drops made of a variety of liquids. While rebound is expected at lower impact velocities on dry ice, at higher impact velocities the drop fragments leaving behind a trail of smaller droplets. However, it is not known whether rebound can be entirely suppressed or fragmentation be controlled on such surfaces and if it depends on the extent of solidification inside the drop. In this work, we report on the role played by solidification within drops in modifying the outcomes of their impact on the supercooled ultra-low adhesive surface of sublimating dry ice. We show that the solidification thickness depends on the impact velocity and is the primary driver in suppression of rebound and also promotes a delay in fragmentation. Our findings imply that sublimating supercooled surfaces can present a broad spectrum of outcomes from complete bouncing to no-rebound which are not seen in drop impacts on supercooled superhydrophobic surfaces. We attribute this to thermo-elastocapillarity which considers bending of the solidified layer and is used to demarcate regime boundaries and determine the coefficient of restitution during rebound.

physics.flu-dyn↗

arXiv2024

Bursting Drops

For decades, researchers worldwide have investigated phenomena related to natural, artificial oil leakages such as oil drop formation within water bodies, their rise, and oil slick evolution after they breach the water-air interface. Despite this, the event leading to slick formation -the bursting of oil drops at the liquid-air interface has remained unnoticed thus far. In this work, we investigate this and report a counterintuitive jetting reversal that releases a daughter oil droplet inside the bulk as opposed to the upwards shooting jets observed in bursting air bubbles. We show that the daughter droplet size thus produced can be correlated to the bulk liquid properties and that its formation can be suppressed by increasing the bulk viscosity or by the addition of microparticles. We further demonstrate the significance of our results by synthesizing colloidal pickered droplets and show applications of bursting compound drops in double emulsions and studies on raindrop impact on a slick. These results could be immensely transformative for diverse areas, including climatology, oceanic, atmospheric sciences, colloidal synthesis and drug delivery.

physics.flu-dyn↗

arXiv2024

Modulating outcomes of oil drops bursting at a water-air interface

Recent studies have shown that capillary waves generated by bursting of an oil drop at the water-air interface produces a daughter droplet inside the bath while part of it floats above it. Successive bursting events produce next generations of daughter droplets, gradually diminishing in size until the entire volume of oil rests atop the water-air interface. In this work, we demonstrate two different ways to modulate this process by modifying the constitution of the drop. Firstly, we introduce hydrophilic clay particles inside the parent oil drop and show that it arrests the cascade of daughter droplet generation preventing it from floating over the water-air interface. Secondly, we show that bursting behavior can be modified by a compound water-oil-air interface made of a film of oil with finite thickness and design a regime map which displays each of these outcomes. We underpin both of these demonstrations by theoretical arguments providing criteria to predict outcomes resulting therein. Lastly, all our scenarios have a direct relation to control of oil-water separation and stability of emulsified solutions in a wide variety of applications which include drug delivery, enhanced oil recovery, oil spills and food processing where a dispersed oil phase tries to separate from a continuous phase.

physics.flu-dyn↗