Efficient Non-Hydrostatic Modeling for Free Surface Waves in Deep and Shallow Water

2009 ◽  
Author(s):  
Chin H. Wu ◽  
Chih-Chieh Young
Keyword(s):  
Free Surface ◽  
Wave Dispersion ◽  
Wave Transformation ◽  
Dispersion Property ◽  
Linear Wave ◽  
Grid System ◽  
Model Free ◽  
Reference Velocity ◽  
Novel Approach ◽  
Hydrostatic Model

A novel approach that introduces the Boussinesq-type like equations into an implicit non-hydrostatic model, free of irrotational flow assumption, is presented. The basic concept is to obtain an analytical-based form of pressure distribution at the top layer by matching the reference velocity under a virtual grid system with the one under a non-hydrostatic model grid system. Locations of the references velocities are tuned to optimize the linear wave dispersion property in the model. Efficiency of this non-hydrostatic model with Boussinesq-type equations (NHM-BTE) is critically examined through several free-surface wave examples. Overall model results show that NHM-BTE using only a few vertical layers (i.e., two ∼ four) is capable of accurately simulating highly dispersive wave motion and wave transformation over irregular bathymetry.

scholarly journals An object-oriented approach to the modelling of free-surface flows

2007 ◽  
Vol 9 (2) ◽  
pp. 81-94 ◽  
Author(s):  
V. Kutija ◽  
M. G. Murray
Keyword(s):  
Free Surface ◽  
Object Oriented ◽  
Free Surface Flows ◽  
Two Dimensions ◽  
Object Oriented Programming ◽  
Programming Approach ◽  
Engineering Practice ◽  
Surface Flows ◽  
Model Free ◽  
Novel Approach

Over the past 40 years many hydraulic modelling systems for free-surface flows have been developed and successfully used in research and engineering practice. These systems were, in general, developed using sequential programming techniques while object-oriented programming approaches have only been used in the development of their visual parts. This paper outlines the approach used in the development of the NOAH modelling systems (Newcastle Object-oriented Advanced Hydroinformatics), developed entirely within the object-oriented paradigm. This novel approach has made NOAH modelling systems computationally highly efficient and yet easy to maintain and extend. NOAH 1D and NOAH 2D are designed to model free-surface flows in one and two dimensions, respectively. NOAH 1D is based on the full de Saint-Venant equations while NOAH 2D is based on the Shallow Water equations. Beside the basic ideas behind the development of NOAH modelling systems this paper also presents their main features and discusses general benefits of the application of the object-oriented programming approach in the development of numerical codes.

The coastal refraction-diffraction wave propagation model

1995 ◽  
Vol 17 (4) ◽  
pp. 6-12
Author(s):  
Nguyen Tien Dat ◽  
Dinh Van Manh ◽  
Nguyen Minh Son
Keyword(s):  
Wave Propagation ◽  
Field Data ◽  
Surf Zone ◽  
Propagation Model ◽  
Wave Transformation ◽  
Diffraction Effect ◽  
Linear Wave ◽  
Diffraction Wave ◽  
Linear Wave Propagation ◽  
Wave Propagation Model

A mathematical model on linear wave propagation toward shore is chosen and corresponding software is built. The wave transformation outside and inside the surf zone is considered including the diffraction effect. The model is tested by laboratory and field data and gave reasonables results.

scholarly journals Extended Elliptic Mild Slope Equation Incorporating the Nonlinear Shoaling Effect

2016 ◽  
Vol 23 (s1) ◽  
pp. 44-51 ◽  
Author(s):  
Qian-lu Xiao ◽  
Chun-hui Li ◽  
Xiao-yan Fu ◽  
Mei-ju Wang
Keyword(s):  
Dispersion Relation ◽  
Nonlinear Wave ◽  
Surf Zone ◽  
Wave Dispersion ◽  
Structure Design ◽  
Coastal Engineering ◽  
Wave Transformation ◽  
Flume Experiments ◽  
Mild Slope Equation ◽  
Wave Shoaling

Abstract The transformation during wave propagation is significantly important for the calculations of hydraulic and coastal engineering, as well as the sediment transport. The exact wave height deformation calculation on the coasts is essential to near-shore hydrodynamics research and the structure design of coastal engineering. According to the wave shoaling results gained from the elliptical cosine wave theory, the nonlinear wave dispersion relation is adopted to develop the expression of the corresponding nonlinear wave shoaling coefficient. Based on the extended elliptic mild slope equation, an efficient wave numerical model is presented in this paper for predicting wave deformation across the complex topography and the surf zone, incorporating the nonlinear wave dispersion relation, the nonlinear wave shoaling coefficient and other energy dissipation factors. Especially, the phenomenon of wave recovery and second breaking could be shown by the present model. The classical Berkhoff single elliptic topography wave tests, the sinusoidal varying topography experiment, and complex composite slopes wave flume experiments are applied to verify the accuracy of the calculation of wave heights. Compared with experimental data, good agreements are found upon single elliptical topography and one-dimensional beach profiles, including uniform slope and step-type profiles. The results indicate that the newly-developed nonlinear wave shoaling coefficient improves the calculated accuracy of wave transformation in the surf zone efficiently, and the wave breaking is the key factor affecting the wave characteristics and need to be considered in the nearshore wave simulations.

scholarly journals Relation between orbital velocities, pressure and surface elevation in non-linear nearshore water waves

2021 ◽  
Author(s):  
Kévin Martins ◽  
Philippe Bonneton ◽  
David Lannes ◽  
Hervé Michallet
Keyword(s):  
Free Surface ◽  
Surface Energy ◽  
Water Waves ◽  
Energy Levels ◽  
Sea Surface ◽  
Surface Elevation ◽  
Linear Wave ◽  
Free Surface Elevation ◽  
High Frequencies ◽  
Non Linear

AbstractThe inability of the linear wave dispersion relation to characterize the dispersive properties of non-linear shoaling and breaking waves in the nearshore has long been recognised. Yet, it remains widely used with linear wave theory to convert between sub-surface pressure, wave orbital velocities and the free surface elevation associated with non-linear nearshore waves. Here, we present a non-linear fully dispersive method for reconstructing the free surface elevation from sub-surface hydrodynamic measurements. This reconstruction requires knowledge of the dispersive properties of the wave field through the dominant wavenumbers magnitude κ, representative in an energy-averaged sense of a mixed sea-state composed of both free and forced components. The present approach is effective starting from intermediate water depths - where non-linear interactions between triads intensify - up to the surf zone, where most wave components are forced and travel approximately at the speed of non-dispersive shallow-water waves. In laboratory conditions, where measurements of κ are available, the non-linear fully dispersive method successfully reconstructs sea-surface energy levels at high frequencies in diverse non-linear and dispersive conditions. In the field, we investigate the potential of a reconstruction that uses a Boussinesq approximation of κ, since such measurements are generally lacking. Overall, the proposed approach offers great potential for collecting more accurate measurements under storm conditions, both in terms of sea-surface energy levels at high frequencies and wave-by-wave statistics (e.g. wave extrema). Through its control on the efficiency of non-linear energy transfers between triads, the spectral bandwidth is shown to greatly influence non-linear effects in the transfer functions between sub-surface hydrodynamics and the sea-surface elevation.

LASRE: A Novel Approach to Large area Accelerated Segmentation for Reverse Engineering on SEM images

2020 ◽  
Author(s):  
Ronald Wilson ◽  
Domenic Forte ◽  
Navid Asadizanjani ◽  
Damon L. Woodard
Keyword(s):  
Integrated Circuits ◽  
Reverse Engineering ◽  
Imaging Modality ◽  
Primary Source ◽  
Time Frame ◽  
Large Area ◽  
Sem Images ◽  
Model Free ◽  
Novel Approach ◽  
Daunting Task

Abstract In the hardware assurance community, Reverse Engineering (RE) is considered a key tool and asset in ensuring the security and reliability of Integrated Circuits (IC). However, with the introduction of advanced node technologies, the application of RE to ICs is turning into a daunting task. This is amplified by the challenges introduced by the imaging modalities such as the Scanning Electron Microscope (SEM) used in acquiring images of ICs. One such challenge is the lack of understanding of the influence of noise in the imaging modality along with its detrimental effect on the quality of images and the overall time frame required for imaging the IC. In this paper, we characterize some aspects of the noise in the image along with its primary source. Furthermore, we use this understanding to propose a novel texture-based segmentation algorithm for SEM images called LASRE. The proposed approach is unsupervised, model-free, robust to the presence of noise and can be applied to all layers of the IC with consistent results. Finally, the results from a comparison study is reported, and the issues associated with the approach are discussed in detail. The approach consistently achieved over 86% accuracy in segmenting various layers in the IC.

scholarly journals Non-linear wave equations for free surface flow over a bump

2020 ◽  
Vol 62 (2) ◽  
pp. 159-169
Author(s):  
Shino Sakaguchi ◽  
Keisuke Nakayama ◽  
Thuy Thi Thu Vu ◽  
Katsuaki Komai ◽  
Peter Nielsen
Keyword(s):  
Free Surface ◽  
Wave Equations ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Linear Wave ◽  
Non Linear ◽  
Linear Wave Equations
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