Flow-induced pruning of branched systems and brittle reconfiguration

TL;DR

This study investigates flow-induced branch breakage in plants, revealing how branching patterns and slenderness influence breakage sequences, and proposes a reconfiguration mechanism that enhances structural resilience under fluid flow.

Contribution

It introduces a new understanding of flow-induced pruning, highlighting the role of geometry and flow in branch breakage and plant survival strategies.

Findings

Branching pattern affects breakage sequence.

Peripheral branch breakage allows higher flow tolerance.

A criterion for branch versus trunk breakage is identified.

Abstract

Whereas most plants are flexible structures that undergo large deformations under flow, another process can occur when the plant is broken by heavy fluid-loading. We investigate here the mechanism of such possible breakage, focusing on the flow-induced pruning that can be observed in plants or aquatic vegetation when parts of the structure break under flow. By computation on an actual tree geometry, a 20-yr-old walnut tree (Juglans Regia L.) and comparison with simple models, we analyze the influence of geometrical and physical parameters on the occurrence of branch breakage and on the successive breaking events occurring in a tree-like structure when the flow velocity is increased. We show that both the branching pattern and the slenderness exponent, defining the branch taper, play a major role in the breakage scenario. We identify a criterion for branch breakage to occur before breakage of the trunk. In that case, we show that the successive breakage of peripheral branches allows the plant to sustain higher flow forces. This mechanism is therefore similar to elastic reconfiguration, and can be seen as a second strategy to overcome critical events, possibly a widespread solution in plants and benthic organisms.