Negative Pressure and Cavitation Dynamics in Plant-like Structures

TL;DR

This paper explores the physics of negative pressure and cavitation in plant-like structures, combining thermodynamic models and experiments to understand water stress phenomena in porous, deformable materials.

Contribution

It introduces a simplified framework for understanding water tension and cavitation in plant-like porous structures, integrating experimental insights with theoretical modeling.

Findings

Water under tension can be metastable in plants.

Cavitation occurs at critical negative pressures, releasing tension.

Artificial structures mimic plant cavitation behavior.

Abstract

It is well known that a solid (e.g. wood or rubber) can be put under tensile stress by pulling on it. Once a critical stress is overcome, the solid breaks, leaving an empty space. Similarly, due to internal cohesion, a liquid can withstand tension (i.e. negative pressure), up to a critical point where a large bubble spontaneously forms, releasing the tension and leaving a void (the bubble). This process is known as cavitation. While water at negative pressure is metastable, such a state can be long-lived. In fact, water under tension is found routinely in the plant kingdom, as a direct effect of dehydration, e.g. by evaporation. In this chapter, we provide a brief overview of occurrences of water stress and cavitation in plants, then use a simple thermodynamic and fluid mechanical framework to describe the basic physics of water stress and cavitation. We focus specifically on situations close to those in plants, that is water at negative pressure nested within a structure that is solid, but porous and potentially deformable. We also discuss insights from these simple models as well as from experiments with artificial structures mimicking some essential aspects of the structures found within plants.