Methodological advances in predicting flow-induced dynamics of plants using mechanical-engineering theory

Abstract

SummaryThe modeling of fluid-structure interactions, such as flow-induced vibrations, is a well -developed field of mechanical engineering. Many methods exist, and it seems natural to apply them to model the behavior of plants, and potentially other cantilever-like biological structures, under flow. Overcoming this disciplinary divide, and the application of such models to biological systems, will significantly advance our understanding of ecological patterns and processes and improve our predictive capabilities. Nonetheless, several methodological issues must first be addressed, which I describe here using two practical examples that have strong similarities: one from agricultural sciences and the other from nuclear engineering. Very similar issues arise in both: individual and collective behavior, small and large space and time scales, porous modeling, standard and extreme events, tradeoff between the surface of exchange and individual or collective risk of damage, variability, hostile environments and, in some aspects, evolution. The conclusion is that, although similar issues do exist, which need to be exploited in some detail, there is a significant gap that requires new developments. It is obvious that living plants grow in and adapt to their environment, which certainly makes plant biomechanics fundamentally distinct from classical mechanical engineering. Moreover, the selection processes in biology and in human engineering are truly different, making the issue of safety different as well. A thorough understanding of these similarities and differences is needed to work efficiently in the application of a mechanistic approach to ecology.

Drag force parameters of rigid and flexible vegetal elements

“…The ability to estimate E for vegetation or other materials remains as a challenge for this technique. It is possible to estimate E for vegetation by assuming a homogeneously solid material and measuring the deflection under load, but there is significant variability in natural vegetation [ de Langre , ], partially due to internal structure and variation caused by turgor pressure [ Niklas , ].…”

Drag measurements in laterally confined 2D canopies: Reconfiguration and sheltering effect

“…46,47 There is also an increasing interest in theoretical models for drag force acting on poro-elastic systems. 19,21,[48][49][50][51] Few studies make explicit the influence of canopy density on drag. Through theoretical modelling, Gosselin and de Langre 52 investigated the effect of surface density on the Vogel exponent of a synthetic poro-elastic system.…”

“…Recent investigations also explore various mechanically activated phenomena in plants or plant canopies that arise from interaction between the fluid flow (air or water) and vegetation. 19 For example, flow-induced vibration and the origin of coherent structures on crop canopies, [20][21][22][23] dissipation of wave energy, 24,25 population growth and ecological consequences, 26 flow-triggered pruning, 27 and seed-dispersal 28,29 were studied. For many such investigations, one of the key ingredients in the analysis is the drag force experienced by a canopy, a plant, and its parts.…”

Changing environments and structure–property relationships in marine biomaterials

“…In materials science, the utility of critical properties depends on the validity of certain assumptions pertaining to the tested specimen including: (1) homogeneity of composition and anisotropy, (2) uniform dimensions and (3) the absence of flaws. These assumptions are rarely if ever fully satisfied in biomaterials (De Langre, 2012). Uniform dimensions, for example, are found in simple solid geometries such as beams, sheets, cylinders and spheres.…”