Wake-induced Oscillations of a Flexible Cylinder in Tandem Orientation with a Rigid Cylinder

Undergraduate #398
Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering

Jakobi Peets - University of the Virgin Islands

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The research project performed in the Fluid-Structure Interactions lab focuses on conducting preliminary scale experiments that will eventually help improve the design and maintenance of mooring lines, such as those used to stabilize offshore wind turbines. The experiments are carried out in a re-circulating water tunnel at Fluid-Structure Interactions laboratory, with a test section of 1.27 m×0.5 m×0.38 m and maximum flow velocity of U=0.3 m/s. These experiments consist of a rigid cylinder, placed in the test-section of the water tunnel, hold fixed at both ends. A flexible cylinder is also placed in the wake of the rigid cylinder. The flexible cylinder is marked with uniformly-distributed black dots along its length. The oscillations of these dots will be captured in the streamwise (inline) and transverse (crossflow) directions using two synchronised high speed cameras (a Phantom Miro 110 and a Panasonic Lumix DMC-FZ200).The captured videos will be the inputs to a tracking software (Tracker) which creates synchronised displacement time histories in the inline and crossflow directions at these discrete points. Previous research has been done on a flexibly mounted rigid cylinder, as well as flexible cylinder placed in flow, which result in large amplitude oscillations of the cylinder, referred to vortex induced vibrations (VIV). The main focus of this research project is to analyze the behavior of the flexible cylinder when placed in the wake of the rigid cylinder. The effect of the distance between the rigid and flexible cylinder on the dynamic response of the system will be investigated through these experiments. Depending on the distance between two cylinders, the flexible cylinder, which is placed downstream of the rigid cylinder, might experience large amplitude oscillation, called wake-induced oscillations. Understanding the physics of the wake-induced oscillations plays an important role in the design schematics, fatigue life, and maintenance of mooring lines.

Funder Acknowledgement(s): National Science Foundation (NSF); Award Number 1460461.

Faculty Advisor: Yahya Modarres-Sadeghi, Modarres@engin.umass.edu

Role: During my research at the Fluid Structure Interactions Laboratory, I processed and interpreted data from previous experiments that were setup. I also made a new setup and conducted an experiment in which all the data was collected to be used for future research.