Momentum tunnelling between nanoscale liquid flows

TL;DR

This paper reveals a novel phenomenon called flow tunnelling in nanoscale liquid flows, where liquids can induce flow in adjacent liquids through electronic interactions, challenging classical hydrodynamics and opening new avenues for controlling fluid transport.

Contribution

It introduces the concept of flow tunnelling driven by electronic excitations, combining many-body theory and molecular simulations to demonstrate this effect.

Findings

Flow of one liquid can induce flow in another behind a separating wall.

Flow tunnelling range is tunable via electronic excitations of the solid.

Maximum tunnelling occurs when electronic excitations resonate with liquid charge fluctuations.

Abstract

The world of nanoscales in fluidics is the frontier where the continuum of fluid mechanics meets the atomic, and even quantum, nature of matter. While water dynamics remains largely classical under extreme confinement, several experiments have recently reported coupling between water transport and the electronic degrees of freedom of the confining materials. This avenue prompts us to reconsider nanoscale hydrodynamic flows under the perspective of interacting excitations, akin to condensed matter frameworks. Here we show, using a combination of many-body theory and molecular simulations, that the flow of a liquid can induce the flow of another liquid behind a separating wall, at odds with the prediction of continuum hydrodynamics. We further show that the range of this 'flow tunnelling' can be tuned through the solid's electronic excitations, with a maximum occurring when these are at resonance with the liquid's charge density fluctuations. Flow tunnelling is expected to play a role in global transport across nanoscale fluidic networks, such as lamellar graphene oxide or MXene membranes. It further suggests exploiting the electronic properties of the confining walls for manipulating liquids via their dielectric spectra, beyond the nature and characteristics of individual molecules.