13,080 research outputs found
Mechanics of a Plant in Fluid Flow
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 specialised scientific developments.
Studying Fluid-Structure Interactions (FSI) in botany, forestry and
agricultural science is crucial to the optimisation of biomass production for
food, energy, and construction materials. FSI 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. We present a short refresher
on fluids mechanics then dive in the statics and dynamics of plant-fluid
interactions. For every phenomenon considered, we present the appropriate
dimensionless numbers to characterise the problem, discuss the implications of
these phenomena on biological processes, and propose future research avenues.
We cover the concept of reconfiguration while considering poroelasticity,
torsion, chirality, buoyancy, and skin friction. We also cover the dynamical
phenomena of wave action, flutter, and vortex-induced vibrations.Comment: 26 pages, 8 figure
Buckling of a beam extruded into highly viscous fluid
Inspired by microscopic paramecies which use trichocyst extrusion to propel
themselves away from thermal aggressions, we propose a macroscopic experiment
to study the stability of a slender beam extruded in a highly viscous fluid.
Piano wires were extruded axially at constant speed in a tank filled with corn
syrup. The force necessary to extrude the wire was measured to increase
linearly at first until the compressive viscous force causes the wire to
buckle. A numerical model, coupling a lengthening elastica formulation with
resistive force theory, predicts a similar behaviour. The model is used to
study the dynamics at large time when the beam is highly deformed. It is found
that at large time, a large deformation regime exists in which the force
necessary to extrude the beam at constant speed becomes constant and
length-independent. With a proper dimensional analysis, the beam can be shown
to buckle at a critical length based on the extrusion speed, the bending
rigidity and the dynamic viscosity of the fluid. Hypothesising that the
trichocysts of paramercies must be sized to maximise their thrust per unit
volume as well as avoid buckling instabilities, we predict that their bending
rigidity must be about . The
verification of this prediction is left for future work.Comment: Accepted for publication in PRE on November 18 2014, 7 pages, 6
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