Abstract

Abstract. Many low-lying tropical and subtropical reef-fringed coasts are vulnerable to inundation during tsunami events. Hence accurate prediction of tsunami wave transformation and run-up over such reefs is a primary concern in the coastal management of hazard mitigation. To overcome the deficiencies of using depth-integrated models in modeling tsunami-like solitary waves interacting with fringing reefs, a three-dimensional (3-D) numerical wave tank based on the computational fluid dynamics (CFD) tool OpenFOAM® is developed in this study. The Navier–Stokes equations for two-phase incompressible flow are solved, using the large eddy simulation (LES) method for turbulence closure and the volume-of-fluid (VOF) method for tracking the free surface. The adopted model is firstly validated by two existing laboratory experiments with various wave conditions and reef configurations. The model is then applied to examine the impacts of varying reef morphologies (fore-reef slope, back-reef slope, lagoon width, reef-crest width) on the solitary wave run-up. The current and vortex evolutions associated with the breaking solitary wave around both the reef crest and the lagoon are also addressed via the numerical simulations.

Highlights

  • A tsunami is an extremely destructive natural disaster, which can be generated by earthquakes, landslides, volcanic eruptions and meteorite impacts

  • To remedy the above deficiencies of using Boussinesqtype models to simulate the solitary processes over the fringing reefs, we develop a 3-D numerical wave tank based on the computational fluid dynamics (CFD) tool OpenFOAM® (Open Field Operation and Manipulation) in this study

  • The flow and vorticity fields associated with the breaking solitary wave around the reef crest and the lagoon are analyzed by the model results

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Summary

Introduction

A tsunami is an extremely destructive natural disaster, which can be generated by earthquakes, landslides, volcanic eruptions and meteorite impacts. As for modeling tsunami waves at a field scale, we are only aware of Kunkel et al.’s (2006) implementation of a nonlinear shallow water model to study the effects of wave forcing and reef morphology variations on the wave run-up. Yao et al (2018) validated a Boussinesq model based on their laboratory experiments to assess the impacts of reef morphologic variations (fore-reef slope, back-reef slope, reef-flat width, reef-crest width) on the solitary wave run-up over the back-reef beach. To remedy the above deficiencies of using Boussinesqtype models to simulate the solitary processes (wave breaking, bore propagation and run-up) over the fringing reefs, we develop a 3-D numerical wave tank based on the computational fluid dynamics (CFD) tool OpenFOAM® (Open Field Operation and Manipulation) in this study. The detailed implementation can be founded in the OpenFOAM® user guide (OpenFOAM Foundation, 2013)

Wave generation and absorption
Experimental settings
Numerical settings
Comparison between numerical and experimental results
Effects of reef morphology variations on the solitary wave run-up
Wave-driven current and vortices around the reef crest and the lagoon
Findings
Conclusions
Full Text
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