Mechanics of a plant in fluid flow

Abstract

Plants live in constantly moving fluid, whether air or water. In response to the loads associated with fluid motion, plants bend and twist, often with great amplitude. These large deformations are not found in traditional engineering application and thus necessitate new specialized scientific developments. Studying fluid–structure interaction (FSI) in botany, forestry, and agricultural science is crucial to the optimization of biomass production for food, energy, and construction materials. FSIs are also central in the study of the ecological adaptation of plants to their environment. This review paper surveys the mechanics of FSI on individual plants. I present a short refresher on fluid mechanics then dive into the statics and dynamics of plant–fluid interactions. For every phenomenon considered, I examine the appropriate dimensionless numbers to characterize the problem, discuss the implications of these phenomena on biological processes, and propose future research avenues. I cover the concept of reconfiguration while considering poroelasticity, torsion, chirality, buoyancy, and skin friction. I also assess the dynamical phenomena of wave action, flutter, and vortex-induced vibrations.

Flow‐induced reconfiguration of aquatic plants, including the impact of leaf sheltering

“…12). A circular plastic sheet (Schouveiler and Boudaoud 2006), representative of some leaves, reconfigures in both the lateral and vertical dimensions, and follows the scaling for 3‐D reconfiguration, F / F r ~ Ca −2/3 , ν = − 4/3 (Schouveiler and Boudaoud 2006; Gosselin et al 2010; Gosselin 2019) for Ca > 1 (dashed line in Fig. 12).…”

“…Several previous studies have developed scaling laws predicting the Vogel exponent for simple structures such as beams, rods, and plates, and an excellent review of these models is provided in Gosselin (2019). For example, at sufficiently high velocity, flat plates, filaments (Gosselin et al 2010; Gosselin and De Langre 2011), and rod‐shaped fibers (Alben et al 2002 exhibit 2‐D reconfiguration, which produces a Vogel number ν = − 2/3.…”

Tropical Biogeomorphic Seagrass Landscapes for Coastal Protection: Persistence and Wave Attenuation During Major Storms Events

“…This swaying motion can cause extra forces of whip-like accelerations (Gaylord and Denny 1997;Gaylord and others 2008), and therefore, our biomechanical measurements may underestimate the forces that the seagrass and calcifying macroalgae experience under wave forces. However, as the seagrass and calcifying algae are relatively short (< 30 cm) (Gaylord and Denny 1997;Bouma and others 2005) and the extra forces from swaying have been shown to only be important when the ratio between wave velocity and current speed is large (Gosselin 2019;Lei and Nepf 2019), the impact of swaying motion is expected to be limited. Given that the tension force required to break the leaves and thalli of the vegetation was an order of magnitude greater than the drag forces simulated during a hurricane, breakage of healthy leaves and thalli of seagrass and calcifying macroalgae is expected to be unlikely during hurricanes.…”

Plant biomechanics in the 21st century

“…How entire plant organs optimized their architectures to survive in the ever-moving waters of an ocean or the turbulence of wind is summarized in two papers in the present issue. Gosselin (2019) provides an overview of the physical framework that can be used to calculate the forces to which plants are exposed by water flow or wind movement. Drag forces and the different types of organ deformation are discussed, and particular attention is given to seaweeds upon exposure to wave action and surface friction.…”