Semester of Graduation

Spring 2023

Degree

Master of Science (MS)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

Mangroves provide shorelines with many beneficial engineering services, including shoreline stabilization, wave attenuation, and damage mitigation during tsunami or tropical cyclone events. This research focuses on wave attenuation rates and drag coefficients, and how they are affected by mangrove prop roots. Previous lab research using a physical wave flume has quantified wave height decay and drag coefficients for synthetic mangrove forests and confirmed that attenuation does indeed increase as mangrove forest density increases. This research will use a 3D numerical flume model developed in Proteus, a Python package, to simulate prior physical model experiments. This work will attempt to validate the numerical flume output, specifically the wave height decay and drag coefficients it yields from an embedded discretization of the mangrove trunk geometry based on the Cut Finite Element Method. This research will then lay the groundwork for the more general approach of using the numerical flume to predict coefficients for real mangrove forests using geometry obtained from LiDAR scans or other site-specific geometric characterizations. The problem solved by this general approach is that wave attenuation and drag coefficients are functions not only of stem and prop root density but more generally of the morphology of the real mangrove system geometry. This varies across multiple scales (prop roots orientations to trunk distributions) and is, therefore, difficult to reproduce in a physical flume. This research supports the advancement of numerical wave flume modeling as an engineering tool for going beyond physical model studies to scenarios where a physical flume may not be available or practical. We show that the numerical wave flume accurately reproduces baseline wave transmission in the Oregon State flume experiments and both baseline and vegetated wave attenuation in the small flume at Patrick F. Taylor Hall. This research can also provide the framework for a more accurate understanding of real-world mangrove forests and their effects on wave attenuation.

Date

4-5-2023

Committee Chair

Chris Kees

DOI

10.31390/gradschool_theses.5766

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