What is it about?
Flexibility allows a leaf to deform under the wind, reducing the amount of drag it creates. However, flexibility also makes the leaf vulnerable to flutter with the fluctuating loads that come with it. Wind tunnel experiments on idealised sheets highlight this trade-off. We find the "optimal" flexibility that allows a plastic sheet to reduce its drag without giving rise to a flutter instability.
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Why is it important?
Storm winds cause damages to urban parks trees, break branches that fall on power lines, and decrease the output of cereal cultures. To better predict these events and simulate them in a context of changing climates, it is crucial to understand the basic mechanisms through which leaves and plants interact with the wind. In the future, models based on this understanding of the wind-plant interactions could be coupled with a weather forecast model to predict the probability of tree or crop damage.
Perspectives
I find the trade-off between drag reduction and flutter brought by flexibility a remarkably interesting question. Too much of a good thing is usually bad. Here like in many other system, there is an amount of flexibility that is "just right": enough to allow the plant to bend in the wind, but not so much that it starts fluttering like a flag.
Frederick Gosselin
Ecole Polytechnique de Montreal
Read the Original
This page is a summary of: Flutter limitation of drag reduction by elastic reconfiguration, Physics of Fluids, February 2024, American Institute of Physics,
DOI: 10.1063/5.0193649.
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