Leaf roll-up and aquaplaning in strong winds and floods

TL;DR

This paper investigates how flexible leaves passively reconfigure in strong winds and floods, reducing drag through mechanisms like roll-up and aquaplaning, with experimental observations of real leaves in flow conditions.

Contribution

It provides experimental evidence of leaf reconfiguration mechanisms in natural flow conditions, linking mechanical properties to passive drag reduction strategies.

Findings

Leaves roll up into cone shapes in wind to reduce flutter and drag

Herbaceous broad leaves aquaplane on water surface during floods

Passive reconfiguration mechanisms are observed in real leaves in flow

Abstract

Flexible plants, fungi, and sessile animals are thought to reconfigure in the wind and water to reduce the drag forces that act upon them. In strong winds, for example, leaves roll up into cone shapes that reduce flutter and drag when compared to paper cut-outs with similar shapes and flexibility. During flash floods, herbaceous broad leaves aquaplane on the surface of the water which reduces drag. Simple mathematical models of a flexible beam immersed in a two-dimensional flow will also reconfigure in flow. What is less understood is how the mechanical properties of a two-dimensional leaf in a three-dimensional flow will passively allow roll up and aquaplaning. In this study, we film leaf roll-up and aquaplaning in tree and vine leaves in both strong winds and water flows.