Structure and flow of low-dimensional water

TL;DR

This paper reviews how water behaves differently in one- and two-dimensional channels, highlighting the effects of reduced dimensionality on its structure, flow, and ionic transport, with implications for understanding water in confined environments.

Contribution

It provides a comprehensive overview of the structural and flow properties of low-dimensional water, emphasizing the role of hydrogen bonding and theoretical approaches.

Findings

Hydrogen bonds stabilize ordered states in low-dimensional water.

Water's flow behavior deviates from classical hydrodynamics in confined channels.

Molecular structure significantly influences ionic transport in low-dimensional water.

Abstract

Water, a subject of human fascination for millennia, is likely the most studied substance on Earth, with an entire scientific field -- hydrodynamics -- dedicated to understanding water in motion. However, when water flows through one-dimensional or two-dimensional channels, its behavior deviates substantially from the principles of hydrodynamics. This is because reducing the dimensionality of any interacting physical system amplifies interaction effects that are beyond the reach of traditional hydrodynamic equations. In low-dimensional water, hydrogen bonds can become stable enough to arrange water molecules into an ordered state, causing water to behave not only like a liquid but also like a solid in certain respects. In this review, we explore the relationship between water's ordering and its ability to flow in low-dimensional channels, using viscosities of bulk water, vapor, and ice as benchmarks. We also provide a brief overview of the key theoretical approaches available for such analyses and discuss ionic transport, which is heavily influenced by the molecular structure of water.