Abstract

With the objective of modeling coastal wave dynamics taking into account nonlinear and dispersive effects, an accurate nonlinear potential flow model is studied. The model is based on the time evolution of two surface quantities: the free surface position and the free surface velocity potential (Zakharov, 1968). The spectral approach of Tian and Sato (2008) is used to resolve vertically the velocity potential in the whole domain, by decomposing the potential using the orthogonal basis of Chebyshev polynomials. The model mathematical theory and numerical development are described, and the model is then validated with the application of three 1DH test cases: (1) propagation of nonlinear regular wave over a submerged bar, (2) propagation of nonlinear irregular waves over a barred beach, and (3) wave generation and propagation after an abrupt deformation of the bottom boundary. These three test cases results agree well with the reference solutions, confirming the model's ability to simulate accurately nonlinear and dispersive waves.

Highlights

  • Coastal and ocean engineers have a growing need for accurate and rapid wave models that are capable of simulating the propagation of waves in the coastal zone, including interactions at the shoreline and with coastal structures

  • A model based on fully nonlinear potential flow theory is developed as a compromise between computationally expensive CFD (Computational Fluid Dynamics) approaches based on the full Navier-Stokes equations, and Boussinesq, Serre-type or GreenNaghdi models that simplify the vertical structure of the dynamics and are only partially nonlinear and/or dispersive

  • Assuming irrotational flow of an inviscid and homogeneous fluid with constant density, the velocity potential Φ(x, z, t) (where x = (x, y)) can be defined. This velocity potential must satisfy the Laplace equation in the fluid domain, which is supplemented by boundary conditions at the free surface z = η(x, t)

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Summary

INTRODUCTION

Coastal and ocean engineers have a growing need for accurate and rapid wave models that are capable of simulating the propagation of waves in the coastal zone, including interactions at the shoreline and with coastal structures. The model is tested and applied to three nonbreaking wave test cases: the propagation of (1) regular nonlinear waves over submerged bar (Dingemans, 1994) and (2) irregular nonlinear waves over a barred beach (Becq-Girard et al, 1999), and (3) wave generation from an impulsive upthrust of the bottom (Hammack, 1973). These test cases are presented and analyzed in part 3

Mathematical model
By defining the velocity potential at the free surface
Numerical model
VALIDATION TEST CASES
Regular waves over a submerged bar
Random waves over a barred beach
Waves generated by impulsive bottom motion
Findings
CONCLUSIONS AND OUTLOOK
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