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Updated: May 28, 2025
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Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions
Published on: February 17, 2019
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Maple samaras recover autorotation following raindrop collisions.
Breanna M Schaeffer1, Tadd T Truscott2, Andrew K Dickerson1
1Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996.
Summary
Samaras demonstrate remarkable resilience to raindrop impacts during flight. These seeds consistently recover autorotation, ensuring effective seed dispersal despite high-speed collisions.
Area of Science:
- Biophysics
- Fluid dynamics
- Plant biomechanics
Background:
- Samaras exhibit stable autorotation, crucial for seed dispersal.
- Falling samaras are susceptible to high-speed raindrop impacts, similar to flying insects.
Purpose of the Study:
- To investigate the dynamics of raindrop collisions with samaras.
- To identify drop-shedding mechanisms enabling autorotation recovery.
- To analyze the impact of collision location and speed on samara behavior.
Main Methods:
- Detailed analysis of collision dynamics across the samara body.
- Observation of drop-shedding mechanisms and autorotation recovery.
- Quantification of pitch, roll, and recovery time post-impact.
Main Results:
- Impacts can induce significant pitch (up to 60 degrees) and spanwise roll.
- Drop behavior varies: shattering, remaining intact, or causing nutlet fragmentation.
- Wingtip impacts yield greatest recovery distance; nutlet impacts are least disruptive.
- Faster drops facilitate quicker shedding and autorotation recovery (<50 ms).
Conclusions:
- Samaras are highly robust to raindrop impacts.
- Autorotation is consistently recovered with minimal reduction in dispersal distance.
- Drop shedding is a key recovery mechanism, influenced by impact dynamics.
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