Physical Review Fluids
Free-space and near-wall dynamics of a flexible sheet sedimenting in Stokes flow
Author(s): Yijiang Yu and Michael D. Graham
We present a numerical study of a thin elastic sheet with small extensibility sedimenting in a viscous fluid in free space or near a wall. The interplay between gravity and the elastic response of sheets gives rise to complex deformation and reorientation dynamics. Near a vertical wall, sheets exhibit asymmetric conformations that cause the sheet to drift toward or away from the wall. Near an inclined wall, sheets show qualitatively different dynamics when the wall angle is large: they either deposit on or slide along the wall with a fixed wall-normal distance.
[Phys. Rev. Fluids 9, 054104] Published Tue May 14, 2024
Increased solidification delays fragmentation and suppresses rebound of impacting drops
Author(s): Varun Kulkarni, Suhas Tamvada, Nikhil Shirdade, Navid Saneie, Venkata Yashasvi Lolla, Vijayprithiv Batheyrameshbapu, and Sushant Anand
Drops impacting supercooled surfaces adhere to them due to contact line pinning and their solidification. However, distinguishing the influence of each phenomenon on post-impact behavior is challenging since even repellent materials exhibit some drop adhesion. In this study, we examine the impact of water and alkane drops on an omniphobic dry ice surface. We show that the solidification extent within the drop, combined with thermal, elastic, and surface tension forces, dictate outcomes like fragmentation, rebound, or no-bounce. Our findings have critical implications for material design in 3D printing, frost-resistant coatings, and safe biological material transport in cold climates.
[Phys. Rev. Fluids 9, 053604] Published Mon May 13, 2024
Contact-angle hysteresis provides resistance to drainage of liquid-infused surfaces in turbulent flows
Author(s): Sofia Saoncella, Si Suo, Johan Sundin, Agastya Parikh, Marcus Hultmark, Wouter Metsola van der Wijngaart, Fredrik Lundell, and Shervin Bagheri
Liquid infused surfaces (LISs) are a nature-inspired surface technology that demonstrates multiple functionalities under laminar and controlled flow conditions. We study experimentally the behavior of the infused lubricant under submerged conditions and turbulent flow. When exposed to turbulence, the lubricant layer develops into a pattern of droplets, the length of which depends on the balance between shear and contact force. The stability of the droplets prevents complete drainage of the lubricant and increases the robustness of the LIS in the presence of turbulence. We identify a model that predicts the equilibrium length of the droplets and validate it with numerical simulations.
[Phys. Rev. Fluids 9, 054002] Published Mon May 13, 2024
Energetic inception of breaking in surface gravity waves under wind forcing
Author(s): Daniel G. Boettger, Shane R. Keating, Michael L. Banner, Russel P. Morison, and Xavier Barthélémy
We examine the influence of wind forcing on the inception of breaking in surface gravity waves using an ensemble of high-resolution numerical simulations. We find that there is a critical point in the energetic evolution of the wave in which the convergence of kinetic energy at the wave crest can no longer be offset by conversion to potential energy, resulting in a rapid growth of kinetic energy up to breaking onset. This energetic signature is shown to consistently differentiate between non-breaking and breaking waves under a range of wind forcing speeds.
[Phys. Rev. Fluids 9, 054803] Published Mon May 13, 2024