14:15 〜 14:30
[SCG62-08] The Science of Dust Bathing
– The Effect of Fiber Structure on Tossing Sand from a Sand Layer –
キーワード：砂浴び、毛構造、斜め衝突
Some birds perform dust bathing, a behavior in which they use their wings or feet to lift and toss sand over their bodies as a form of self-maintenance. However, the physical processes governing dust bathing behavior remain largely unexplored, and the functional evaluation of bird feather design in relation to this behavior is still insufficient.
In this study, we investigated how the flexibility of fibrous structures like feather influences the tossing behavior of sand when a brush (simple bundle of fibers) is used to sweep a sand layer, simulating wing-assisted dust bathing.
To examine this, we conducted an experiment in which a pendulum with a brush at its tip swept the surface of a sand layer, and the resulting sand tossing behavior was observed. The results obtained demonstrated that:
When a brush with soft fibers was used, significant deformation of the fibers was induced by the sweeping impact, leading to sand accumulation at the tip of the brush. After that, the elastic response of the fibers tossed the sand forward.
In contrast, when a brush with stiff fibers was used, the deformation upon impact was negligible, causing the sand to stack vertically. The accumulated sand then received momentum from the pendulum's inertia and was subsequently tossed forward.
The difference in tossing behavior led to variations in tossing amount (M), tossing velocity (V), and tossing angle (θ) of sand depending on the experimental conditions. Specifically, the tossing velocity (V) tended to increase with increasing impact velocity (v0). When using stiff fibers, V was almost equal to v0. However, when using soft fibers, V/v0 increased as v0 became larger, and this ratio was greater for thinner fibers. Its range is about 1-1.4.
By analyzing the deformation of fiber tips during the sweeping motion, we estimated the force applied to the sand and elucidated the role of fiber stiffness in determining tossing behavior. Furthermore, by defining and estimating an efficiency function for sand tossing in the context of dust bathing behavior, we found that the optimal impact velocity for efficient sand tossing differs depending on fiber stiffness.
In this study, we investigated how the flexibility of fibrous structures like feather influences the tossing behavior of sand when a brush (simple bundle of fibers) is used to sweep a sand layer, simulating wing-assisted dust bathing.
To examine this, we conducted an experiment in which a pendulum with a brush at its tip swept the surface of a sand layer, and the resulting sand tossing behavior was observed. The results obtained demonstrated that:
When a brush with soft fibers was used, significant deformation of the fibers was induced by the sweeping impact, leading to sand accumulation at the tip of the brush. After that, the elastic response of the fibers tossed the sand forward.
In contrast, when a brush with stiff fibers was used, the deformation upon impact was negligible, causing the sand to stack vertically. The accumulated sand then received momentum from the pendulum's inertia and was subsequently tossed forward.
The difference in tossing behavior led to variations in tossing amount (M), tossing velocity (V), and tossing angle (θ) of sand depending on the experimental conditions. Specifically, the tossing velocity (V) tended to increase with increasing impact velocity (v0). When using stiff fibers, V was almost equal to v0. However, when using soft fibers, V/v0 increased as v0 became larger, and this ratio was greater for thinner fibers. Its range is about 1-1.4.
By analyzing the deformation of fiber tips during the sweeping motion, we estimated the force applied to the sand and elucidated the role of fiber stiffness in determining tossing behavior. Furthermore, by defining and estimating an efficiency function for sand tossing in the context of dust bathing behavior, we found that the optimal impact velocity for efficient sand tossing differs depending on fiber stiffness.