arXiv subjects

Sandip Dighe

Publications and source records attributed to Sandip Dighe.

3 recordsLinked to original sources

arXiv2026

Impulse-driven capillary detachment

Capillary interfaces subjected to impulsive forcing arise in many natural and technological systems, yet the pathway by which rapid substrate motion is converted into droplet detachment remains unclear. Here we study this process in a controlled setting: a liquid droplet resting on a taut wire that is plucked and suddenly released. The resulting transverse wave imparts a brief inertial forcing at the droplet base, initiating rapid stretching that precedes sheet formation and jet breakup. We show that the maximum extension prior to detachment is set by the mechanical work transmitted from the wire through capillary traction at the three-phase contact line, balanced by viscous dissipation during filament extension. This energetic balance identifies the contact line as the pathway by which mechanical impulse is converted into capillary deformation and governs impulsive droplet detachment.

physics.flu-dyn↗

arXiv2026

Effect of initial Rayleigh mode on drop deformation under impulsive acceleration

One of the fundamental ways of representing a droplet shape is through its Rayleigh-modes, where each mode corresponds to distinct surface-energy. Previous studies have focused on the effect of these modes on free oscillations of drops. In this paper, we systematically quantify how the different prescribed initial axisymmetric Rayleigh modes modulate aerodynamic energy uptake and the resulting deformation of an impulsively accelerated drop. Using experimentally validated VOF-based multiphase numerical simulations, we isolate the coupled effects of finite-amplitude surface oscillation modes and the associated initial surface-energy state by initializing the drops with well-defined $(n,0)$ modes and phases $\{0,\pi\}$, while conserving the equivalent drop volume. We find that the deformation outcome is governed by the drag due to the drop's initial geometry, and the dynamic coupling between the free modal oscillations and the forced aerodynamic deformation. We find that constructive superposition amplify deformation, whereas destructive superposition can stabilize the drop even when the aerodynamic forcing is sufficient to deform an analogous spherical drop to breakup. Initial modes and phases that channel a larger fraction of the input power into deformation, in the form of oscillatory kinetic energy and additional surface energy, attain larger deformations and are closer to the fragmentation threshold. These coupling effects are especially pronounced in high-viscosity systems, where viscous dissipation is large and facilitates the transfer of a larger fraction of the total energy to translational kinetic energy instead of oscillatory kinetic energy. For low density-ratio systems, early-time coupling and energy transfer is the dominant mechanism that governs drop deformation.

physics.flu-dyn↗

arXiv2024

Rayleigh-Plateau Instability on an angled and eccentric fiber: An alternative approach

This research explores the modulation of Rayleigh-Plateau instability by adjusting the orientation angle and eccentricity of a wire within a nozzle. We demonstrate that both the angle and eccentricity significantly influence the Rayleigh-Plateau instability regimes. They both also influence characteristics, such as bead velocity along the wire, bead spacing (wavelength), and bead volume. Notably, when wires are both angled and eccentric, the effect of angle prevails. Our approach includes an empirical scaling analysis, comparing gravity, curvature-induced force, and viscosity forces on a single bead, yielding a unified empirical viscous force law, and enhancing understanding of Rayleigh-Plateau regime dynamics. This new framework enriches our understanding of the forces at play in Rayleigh-Plateau instability and provides practical insights into the manipulation of fluid dynamics in industrial applications.

physics.flu-dyn↗