A NUMERICAL SIMULATION OF THE WOS AND THE WAVE PROPAGATION ALONG A COASTAL DIKE

2012 ◽  
Vol 1 (33) ◽  
pp. 49 ◽  
Author(s):  
Panayotis Prinos ◽  
Maria Tsakiri ◽  
Dimitris Souliotis
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Free Surface ◽  
Numerical Models ◽  
Field Measurements ◽  
Air Entrainment ◽  
Empirical Relationships ◽  
Wave Overtopping ◽  
Unsteady Rans ◽  
The Waves

Wave overtopping and the propagation of the waves on the crest and the landward slope of a coastal dike is investigated numerically. Wave overtopping conditions are simulated using the concept of the Wave Overtopping Simulator (WOS). Two numerical models of the WOS are constructed using the FLUENT 6.0.12 (FLUENT Inc. 2001) and the FLOW 3D 9.4 (FLOW 3D 2010) CFD codes. The former simulates the WOS without accounting for air entrainment while the latter accounts for air entrainment. The unsteady RANS equations, the RNG k-ε turbulence model and the VOF method are solved numerically, for "tracking" the free surface and the head of the "current" from the dike crest to the landward dike slope. The computed results from the two models are compared with each other and also against field measurements and proposed empirical relationships (Van der Meer et al. 2010).

Free surface over a horizontal shear layer: vorticity generation and air entrainment mechanisms

2017 ◽  
Vol 813 ◽  
pp. 1007-1044 ◽  
Author(s):  
Matthieu A. André ◽  
Philippe M. Bardet
Keyword(s):  
Free Surface ◽  
Shear Layer ◽  
Air Entrainment ◽  
Horizontal Shear ◽  
Vortex Instability ◽  
Image Velocimetry ◽  
Planar Laser ◽  
Spatio Temporal ◽  
The Waves

Two air entrainment mechanisms driven by vortex instability are reported in the unstable relaxation of a horizontal shear layer below a free surface. This flow is experimentally investigated by means of planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) coupled with surface profilometry. PLIF identifies counter-rotating vortex pairs (CRVP) emanating from the surface following the growth of high steepness two-dimensional millimetre-size waves for Reynolds and Weber numbers based on the momentum thickness of 177 to 222 and 7.59 to 13.9, respectively. High spatio-temporal resolution PIV reveals the role of surface-generated vorticity and flow separation in the highly curved trough of the waves on the injection of a CRVP. Air bubbles are entrapped in the wake of these CRVPs at Reynolds number above 190. PIV data and spanwise PLIF images show two initiation mechanisms: primary vortex instability modulating the spanwise location where the flow separates, resulting in the pinch off of an air ligament, and secondary vortex instability turning a CRVP into$\unicode[STIX]{x1D6FA}$-shaped loops pulling the surface down. Instability wavelengths agree with linear stability analysis, and models for these new air entrainment mechanisms are proposed.

Spurious multiples in seismic interferometry of primaries

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. SI111-SI124 ◽  
Author(s):  
Roel Snieder ◽  
Kees Wapenaar ◽  
Ken Larner
Keyword(s):  
Wave Propagation ◽  
Free Surface ◽  
Homogeneous Medium ◽  
Physical Principle ◽  
Seismic Interferometry ◽  
Heuristic Argument ◽  
Direct Wave ◽  
Reflected Waves ◽  
The Waves ◽  
Insight Into

Seismic interferometry is a technique for estimating the Green’s function that accounts for wave propagation between receivers by correlating the waves recorded at these receivers. We present a derivation of this principle based on the method of stationary phase. Although this derivation is intended to be educational, applicable to simple media only, it provides insight into the physical principle of seismic interferometry. In a homogeneous medium with one horizontal reflector and without a free surface, the correlation of the waves recorded at two receivers correctly gives both the direct wave and the singly reflected waves. When more reflectors are present, a product of the singly reflected waves occurs in the crosscorrelation that leads to spurious multiples when the waves are excited at the surface only. We give a heuristic argument that these spurious multiples disappear when sources below the reflectors are included. We also extend the derivation to a smoothly varying heterogeneous background medium.

scholarly journals NUMERICAL SIMULATION OF BERM AND DUNE EROSION DUE TO WAVE OVERTOPPING AND SEDIMENT OVERWASH USING OPENFOAM

2018 ◽  
pp. 29
Author(s):  
Nikolaos Karagiannis ◽  
Theophanis Karambas ◽  
Christopher Koutitas
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Hydrodynamic Model ◽  
Coastal Dynamics ◽  
Wave Overtopping ◽  
Dune Erosion ◽  
Equilibrium Profile

The present work follows authors’ previous works, published and presented at ICCE 2016 and Coastal Dynamics 2017 conferences (Karagiannis et al. 2016, 2017) and concerns the numerical simulation of berm and dune cross-shore profile evolution due to wave overtopping and sediment overwash through an innovative repetitive approach of coupling a hydrodynamic model, synthesized on the OpenFoam platform with a morphodynamic one, whose origin code is developed in FORTRAN by the authors. The hydrodynamic model is used for the wave propagation, while the morphodynamic one gets the results of the first model and yields the new cross-shore seabed formation. The above process is repeated until the equilibrium profile is achieved.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

scholarly journals A Computational Approach to Solve a System of Transcendental Equations with Multi-Functions and Multi-Variables

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 920
Author(s):  
Chukwuma Ogbonnaya ◽  
Chamil Abeykoon ◽  
Adel Nasser ◽  
Ali Turan
Keyword(s):  
Numerical Models ◽  
Problem Formulation ◽  
Science And Engineering ◽  
Physical Systems ◽  
Engineering Problems ◽  
Parametric Studies ◽  
Independent Variable ◽  
Transcendental Equations ◽  
The Waves ◽  
Modelling Approach

A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophotovoltaic systems were also highlighted. Overall, solutions to SoTEs present new opportunities for including more functions and variables in numerical models of systems, which will ultimately lead to a more robust representation of physical systems.

scholarly journals Experimental and Computational Approach to Fatigue Behavior of Polycrystalline Tantalum

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 416 ◽  
Author(s):  
Damien Colas ◽  
Eric Finot ◽  
Sylvain Flouriot ◽  
Samuel Forest ◽  
Matthieu Mazière ◽  
...  
Keyword(s):  
Free Surface ◽  
Low Cycle Fatigue ◽  
Large Strain ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Field Measurements ◽  
Test Sample ◽  
Lattice Rotation ◽  
Element Simulation ◽  
Crack Initiation Criterion

This work provides an experimental and computational analysis of low cycle fatigue of a tantalum polycrystalline aggregate. The experimental results include strain field and lattice rotation field measurements at the free surface of a tension–compression test sample after 100, 1000, 2000, and 3000 cycles at ±0.2% overall strain. They reveal the development of strong heterogeneites of strain, plastic slip activity, and surface roughness during cycling. Intergranular and transgranular cracks are observed after 5000 cycles. The Crystal Plasticity Finite Element simulation recording more than 1000 cycles confirms the large strain dispersion at the free surface and shows evidence of strong local ratcheting phenomena occurring in particular at some grain boundaries. The amount of ratcheting plastic strain at each cycle is used as the main ingredient of a new local fatigue crack initiation criterion.

scholarly journals Experimental and Numerical Investigation of 3D Dam-Break Wave Propagation in an Enclosed Domain with Dry and Wet Bottom

2021 ◽  
Vol 11 (12) ◽  
pp. 5638
Author(s):  
Selahattin Kocaman ◽  
Stefania Evangelista ◽  
Hasan Guzel ◽  
Kaan Dal ◽  
Ada Yilmaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Numerical Models ◽  
Three Dimensional ◽  
Dam Break ◽  
Dam Failure ◽  
Navier Stokes ◽  
Negative Wave ◽  
Through Flow ◽  
Instantaneous Removal ◽  
Surface Patterns

Dam-break flood waves represent a severe threat to people and properties located in downstream regions. Although dam failure has been among the main subjects investigated in academia, little effort has been made toward investigating wave propagation under the influence of tailwater depth. This work presents three-dimensional (3D) numerical simulations of laboratory experiments of dam-breaks with tailwater performed at the Laboratory of Hydraulics of Iskenderun Technical University, Turkey. The dam-break wave was generated by the instantaneous removal of a sluice gate positioned at the center of a transversal wall forming the reservoir. Specifically, in order to understand the influence of tailwater level on wave propagation, three tests were conducted under the conditions of dry and wet downstream bottom with two different tailwater depths, respectively. The present research analyzes the propagation of the positive and negative wave originated by the dam-break, as well as the wave reflection against the channel’s downstream closed boundary. Digital image processing was used to track water surface patterns, and ultrasonic sensors were positioned at five different locations along the channel in order to obtain water stage hydrographs. Laboratory measurements were compared against the numerical results obtained through FLOW-3D commercial software, solving the 3D Reynolds-Averaged Navier–Stokes (RANS) with the k-ε turbulence model for closure, and Shallow Water Equations (SWEs). The comparison achieved a reasonable agreement with both numerical models, although the RANS showed in general, as expected, a better performance.

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