Latest papers in fluid mechanics

Author(s): Nathan D. Jones, Adrian Moure, and Xiaojing Fu

Gravity-driven flow of water into unsaturated porous media can form preferential pathways due to the gravity fingering instability. Here, we consider this process in a subfreezing porous medium using numerical simulations. We find that the macroscopic infiltration rate can be well predicted by the freezing Damköhler number. In contrast to the classical instability, the introduction of freezing in this problem gives rise to a new flow regime in which secondary flow pathways form in between the initial channels. This secondary instability homogenizes the otherwise channelized flow field and decreases the effective infiltration velocity.

[Phys. Rev. Fluids 9, 123802] Published Mon Dec 02, 2024

Author(s): Chengzhen Sun, Qiyuan Wang, Mehdi Neek-Amal, Runfeng Zhou, and Bofeng Bai

In angstrom-scale channels, where water forms a two-dimensional (2D) monolayer, interlayer shear force decreases, making traditional viscosity definitions unsuitable. Our findings demonstrate that in channels below 1 nm, water flow does not follow conventional viscosity-driven principles; instead, friction between water molecules and channel walls governs flow behavior. We extend the Hagen-Poiseuille equation by excluding viscosity and emphasizing friction, providing a more accurate model for flow in ultra-narrow 2D spaces. This approach improves understanding of water flow in angstrom-scale channels, with applications in desalination and energy conversion.

[Phys. Rev. Fluids 9, 124201] Published Mon Dec 02, 2024

Author(s): Sergio Portillo, Javier Cervera, Salvador Mafe, and Patricio Ramirez

A multipore membrane with current-rectifying nanofluidic diodes exhibits memristive properties based on the surface-charge-regulated ionic transport. The neuromorphiclike potentiation of the conductance by voltage pulses provides different functionalities that can be modulated not only by the amplit…

[Phys. Rev. E 110, 065101] Published Mon Dec 02, 2024