Author: Yeung, Wai Kin
Title: Free falling of eccentric cylinder in quiescent water
Advisors: Tang, Hui (ME)
Degree: M.Sc.
Year: 2021
Subject: Fluid mechanics
Hong Kong Polytechnic University -- Dissertations
Department: Department of Mechanical Engineering
Pages: vi, 74 pages : color illustrations
Language: English
Abstract: The decent motion of a freely falling object is a common phenomenon observed in our daily involves some classical but interesting problems in fluid mechanics. The behavior of a falling object in the fluid is generally complex even for the simplest geometry of a 2-dimensional cylinder. Previous researcher had studied different shape of objects like 2-dimensional plate, 2-dimensional cylinder, disk, sphere or even the irregular shaped seeds found in the nature. The trajectories of solid thin objects like plate, disk, feather, or leaf are observed to have different combination of gliding and rotating motion that result in three types of falling regimes including fluttering motion, transitional motion and tumbling motion. People had also studied the simplest geometry of a 2-dimensional cylinder, but most of them focus on the average drag force and coefficient and not yet for the rotation behavior due to a nonlinear drag relationship. According to the famous Kármán vortex street, at a certain range of Reynolds numbers, is a repeating pattern of swirling vortices will be formed and causing it to vibrate. In fact, the vortex street will not only force a cylinder to vibrate, moreover may roll the cylinder. The main purpose of this dissertation is to build up experimental apparatus and try to study the interaction between a free-falling rolling cylinder and the fluid. The cylinder was released in a glass tank with quiescent water, and its trajectory was recorded using a vertical moving camera. The Instantaneous and average kinematic parameters, including midpoint trajectories and descent angle variation, will be analyzed.
Rights: All rights reserved
Access: restricted access

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