First Advisor

Raul Bayoan Cal

Term of Graduation

Winter 2025

Date of Publication

1-7-2025

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Mechanical Engineering

Department

Mechanical and Materials Engineering

Language

English

Subjects

ocean, offshore wind, turbulence, vorticity, wave

Physical Description

1 online resource (ix, 71 pages)

Abstract

The interactions between wind and waves in offshore environments are complex and have yet to be fully understood. Analyzing these interactions is motivated by an increased interest in climate modeling and the deployment of offshore construction, such as offshore wind farms. In this study, experiments are performed in a wind tunnel using particle image velocimetry (PIV) to analyze wind-wave interactions over various wave and wind speeds. The addition of the wave, a moving boundary, leads to the use of Reynolds triple decomposition in order to separate the turbulent and wave-phase coherent fluctuations. A curvilinear coordinate system was used to analyze the wave's affects on velocity, vorticity and energy transport in the air field above. The two-point correlations indicate that the magnitude and size of air flow structures are dependent on wave phase and wave properties. Cross-correlation of vorticity to velocity components reveal positive and negative correlation lobes due to the clockwise rotation of the air. A control surface analysis using the mean kinetic energy(MKE) equation revealed that the magnitude the energy fluxes and momentum exchange between the wind and the waves decreased with wavelength and are more prominent at specific wave phases. These trends are more pronounced at higher wind speeds but are not dependent the Reynolds number. Analysis of the residuals of the MKE equation highlights the critical role of pressure in energy and momentum fluxes at the air-water interface. These findings enhance our understanding of ocean wave and atmospheric boundary layer interactions, leading to more accurate weather and climate models, while also contributing to the longevity and improving power production in offshore wind farms.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/43268

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