Hydrodynamic Coupling Distance for an Immersed Pendulum Approaching Toward a Nearby Solid Boundary
Date Issued
2011
Date
2011
Author(s)
Zheng, You-Yuan
Abstract
This research examines the unsteady pendulum motion in viscous fluid with the presence of a second solid boundary with high-speed imaging technique. It is observed that when a pendulum moves perpendicularly towards a solid boundary, the pendulum velocity decelerates before contact. A hydrodynamic coupling distance is proposed in this work to characterize the degree of influence of a second stationary target on the immersed pendulum motion. This coupling distance is observed to increase monotonically with diminishing pendulum Reynolds number (Re) and Stokes number (St) and with the target size.
In the experiments, a range of Re and St were achieved by using different pendulum size, release angle, particle and liquid densities. The captured high-speed image sequence was processed by Circular Hough Transform method to locate the incident sphere center which was further employed to estimate pendulum velocity.
The pendulum motion was normalized by a free pendulum motion generated using identical pendulum, liquid, and release angle but without the presence of a second solid boundary. The location where the two pendulum motion deviate from each other is used to define the so-called hydrodynamic coupling distance. Afterwards, we apply Non-dimensionalize methods to compare the free pendulum with the one that influence by a solid boundary. Thus, the coupling distance is found by estimating the decreasing rate of the velocity.
Subjects
immersed pendulum motion
hydrodynamic coupling distance
boundary effects
granular flow
viscous flow
Type
thesis
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