What is it about?

Aeolian transport is responsible for a range of geomorphic processes shaping Earth (and other planets, e.g. Mars) surface. It’s also relevant for the transport of plastics that end up at sea, polluting our oceans. Incipient motion of aeolian entrainment has been studied for decades. In this experimental study we use novel tools to obtain high resolution measurements of the initial stages of particle’s motion and identify for a first time distinct angular displacement thresholds below which only twitching (rocking) motions occur and above which the particle is rolling out of its pocket and is fully transported in saltation mode.

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Why is it important?

We define for a first time angular displacement thresholds that can be used to classify the twitching (rocking) and rolling motions (full entrainment). This is important as the frequency of occurrence of the rocking and rolling events, relates to the change of near bed surface aerodynamic conditions responsible for aeolian bedload transport. This research is the first step towards identifying new tools and ways of better monitoring the risk of infrastructure destabilisation due to aeolian transport.

Perspectives

Dr. Manousos Valyrakis said: “The findings from this study are an exciting step towards developing new tools and methods for assessing aerodynamic entrainment risks. This research is inspired by recent conceptual and theoretical progress in the field of transport of coarse material due to turbulent flows (in water or air). The ambition is to further realise and enable real world applications of this research by exploiting technical advancements that now allow for bringing the highly resolved observations of particle motion from the lab into the field. I have enjoyed this many years, international and multi-institutional collaboration and I am pleased to see it coming to fruition.”

Manousos Valyrakis

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This page is a summary of: Rock and roll: Incipient aeolian entrainment of coarse particles, Physics of Fluids, July 2021, American Institute of Physics, DOI: 10.1063/5.0047604.
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