Swirling Fluid Reduces the Bounce of Partially Filled Containers

Certain spatial distributions of water inside partially filled containers can significantly reduce the bounce of the container. In experiments with containers filled to a volume fraction $\varphi$, we show that rotation offers control and high efficiency in setting such distributions and, consequently, in altering bounce markedly. High-speed imaging evidences the physics of the phenomenon and reveals a rich sequence of fluid-dynamics processes, which we translate into a model that captures our overall experimental findings.

Figure 1

Impact of partially filled containers. (a) Sequence of images for a container dropped with a quiescent fluid inside. (b) Sequence when the container is rotated at frequency $\mathrm{\Omega }=12\mathrm{rev}/\mathrm{s}$ before release. (c) Trajectories for the lowest point of the container for the same time interval as panels (a) and (b).

Figure 2

The experimental setup consists of a system for bottle rotation and release, video sequencing of impact, and a hoist for relocating the bottle and resuming measurements. The discontinuity indicates that the release height is much larger than shown.

Figure 3

Restitution coefficient quantifying the water-damping effect. (a) Dependence of the restitution coefficient as a function of the bottle rotation $\mathrm{\Omega }$ before release. (b) Dependence of the restitution coefficient as a function of the bottle filling volume fraction $\varphi$.

Figure 4

Fluid dynamical processes reducing bottle bounce. (a) Four main stages summarize the motion: forced rotation, free fall, impact, and bounce-off. Experimental examples are presented in (b) and (c) as image sequences equally spaced in time and shown in the bottle reference frame. (b) Climbing front during free fall from $t_r^{-}$ to almost $t=0^{-}$, spanning 375 ms. (c) Impact and bounce-off in a single sequence going from $t=0^{+}$ to $t_b$ in 37 ms. The white bar in panel (c) indicates the bottle diameter of 60 mm.

Figure 5

Comparison between experimental data and the model. We used ${\mathrm{\Pi }}_l=0.982$, ${\mathrm{\Pi }}_{\mathrm{\Omega }}=0.525$, ${\mathrm{\Pi }}_e=27$, and ${\mathrm{\Pi }}_d=0.0583$ for the model, and experimental data for the largest $\mathrm{\Omega }$ explored, where the modeling hypotheses are fulfilled. The last data point drop is due to container plastic deformations occurring during impact.