In this paper, we study the propagation and run-up of long tsunami-like waves in the 300 m long Large Wave Flume (GWK), Hannover, Germany and analyze the feasibility of experiments on tsunami run-up in large facilities. This paper is the continuation of our previous paper (Schimmels et al., 2015, companion paper). The propagation of long period waves over large distances for different shapes is studied experimentally and numerically. Fully nonlinear potential flow theory has been used to model these cases numerically along with Korteweg-de Vries simulations. The theoretical explanation of the observed effects has been discussed. The run-up characteristics of the studied waves with respect to their shape and beach slope were also investigated. Further, a downscaled real tsunami time series is also reproduced experimentally and studied with regard to its possible run-up. © 2015 Elsevier B.V.

V Sriram

Department of Ocean Engineering

I. Didenkulova

A. Sergeeva

S. Schimmels

KORTEWEG-DE VRIES EQUATION

Nonlinear equations

Numerical models

Wave propagation

Experimental facilities

FULLY NONLINEAR

Long waves

physical model

TSUNAMI WAVES

Tsunamis

coastal zone

experimental study

feasibility study

NEARSHORE DYNAMICS

theoretical study

Tsunami

Wave modeling

WAVE RUNUP

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Coastal Engineering

In this paper, the results of the study on the wave propagation and breaking of solitons and N-waves in fresh water and brine are reported. The experiments were performed in the twin flume facility at the Franzius Institute, Leibniz University of Hannover. Brine from Dead Sea was used for the study. The objective of the experimental study was to determine the flood safety levels along the banks of the Dead Sea and to arrive at the empirical equations for run-up. A weakly coupled numerical model based on the fully nonlinear potential flow and Navier–Stokes equation was used to validate the experimental results. The proposed numerical model is in good agreement with the present experimental results and the available analytical solutions for run-up estimation. The breaking N-waves were found to have a reduced run-up when compared to breaking solitons. The paper shows that the long wave propagation and run-up in both brine and water has similar characteristics. © 2017 International Association for Hydro-Environment Engineering and Research.

Journal of Hydraulic Research

Propagation and breaking characteristics of solitons and N-wave in fresh water and brine

Experimental studies on tsunami are carried out since many years, most of them by generating solitary waves with a piston type wave maker. However, today it is more and more appreciated that these kinds of waves actually do not represent a real tsunami very well, as particularly for the shallow waters at the coast the wave length becomes comparably far too short. Recently new generation methods for scaled down real tsunami experiments were suggested, as it was doubted that sufficiently long waves could be generated with a classical wave maker. The present paper shall disprove these arguments by providing results of a study carried out in the Large Wave Flume (Großer Wellenkanal, GWK), where waves of periods between 30s and more than 100s at 1m water depth were successfully generated with a piston type wave maker. Results for elongated solitary waves, trough led N-waves and real tsunami records as a combination of a different number of general solitons (sech2 waves) are presented. Finally, the requirements and limitations to bring a "real" tsunami into the laboratory are discussed. © 2015 Elsevier B.V.

Tsunami generation in a large scale experimental facility

This is the first paper to present a hybrid method coupling an Improved Meshless Local Petrov Galerkin method with Rankine source solution (IMLPG_R) based on the Navier-Stokes (NS) equations, with a finite element method (FEM) based on the fully nonlinear potential flow theory (FNPT) in order to efficiently simulate the violent waves and their interaction with marine structures. The two models are strongly coupled in space and time domains using a moving overlapping zone, wherein the information from both the solvers is exchanged. In the time domain, the Runge-Kutta 2nd order method is nested with a predictor-corrector scheme. In the space domain, numerical techniques including 'Feeding Particles' and two-layer particle interpolation with relaxation coefficients are introduced to achieve the robust coupling of the two models. The properties and behaviours of the new hybrid model are tested by modelling a regular wave, solitary wave and Cnoidal wave including breaking and overtopping. It is validated by comparing the results of the method with analytical solutions, results from other methods and experimental data. The paper demonstrates that the method can produce satisfactory results but uses much less computational time compared with a method based on the full NS model. © 2014 Elsevier Inc.

Fulltext

Journal of Computational Physics

A hybrid method for modelling two dimensional non-breaking and breaking waves

A proper design of offshore and coastal structures requires further knowledge about extreme wave events. Such waves are highly nonlinear and may occur unexpectedly due to diverse reasons. One of these reasons is wave-wave interaction and the wave focusing technique represents one option to generate extreme wave events in the laboratory. The underlying mechanism is the superimposition and phasing of wave components at a predefined location. To date, most of the existing methods to propagate target wave profile backwards to the position of the wave generator apply linear wave theory. The problem is that the generated waves with different frequencies generate new components which do not satisfy the linear dispersion relation. As a result, small changes in the wave board control signal generally induce large and random shifts in the resulting focused wave. This means that iterations are necessary to get the required wave profile at the correct position in the flume. In this study, a Self Correcting Method (SCM) is applied to optimize the control signal of the wave maker in a Numerical Wave Tank (NWT). The nonlinearities are included in the control signal and accurate wave focusing is obtained irrespective of the prevailing seabed topography (horizontal or sloping) and type of structure (reflective or absorbing). The performance of the proposed SCM is numerically investigated for a wide variety of scenarios and validated by scale model tests in the Large Wave Flume (Großer Wellen Kanal, GWK), Hannover, Germany. Moreover, the application of the proposed SCM in the Numerical Wave Tank to generate a tsunami at a predefined position and the comparison of the results with the time series recorded in the Pago Pago harbour (Samoa) is very encouraging. The strengths and limitations of the proposed SCM are discussed, including the potential for further developments. © 2014 Elsevier B.V.

Extreme wave generation using self correcting method - revisited

Numerical simulation of nonlinear waves to reproduce the laboratory measurements has been a topic of great interest in the recent past. The results reported in the literature are mainly focused on qualitative comparison or on the relative errors between the numerical simulation and measurements in laboratory and hence lack in revealing the existence of phase shift in nonlinear wave simulation. In this paper, the simulation of nonlinear waves in mixed Eulerian and Lagrangian framework using finite element method (FEM) is investigated by applying two different velocity calculation methods viz, cubic spline and least squares (LS). The simulated wave surface elevation has been compared with the experimental measurements. The coherence analysis has been carried out using the wavelet transformation, which gives a better understanding between the numerical and the experimental results with respect to the time-frequency space, compared with the conventional Fourier transformation. It is observed that the application of cubic spline approach leads to a higher phase difference for steeper waves. The present study has shown that the phase difference exists at the higher modes rather than at the primary period. For waves with steepness (wave height/wave length) higher than 0.04, LS approach is found to be effective in capturing the higher-order frequency components in the event of nonlinearity. In addition, the comparison of numerical simulations with that from PIV measurements for the tests with solitary waves is also reported. Copyright © 2009 John Wiley &amp; Sons, Ltd.

International Journal for Numerical Methods in Fluids

Quantification of phase shift in the simulation of shallow water waves

In this article, tsunamis represented as solitary waves was simulated using the fully nonlinear free surface waves based on Finite Element method developed by Sriram et al. (2006). The split up of solitary wave while it propagates over the uneven bottom topography is successfully established. Wave transmission and reflection over a vertical step introduced in the bottom topography is in good agreement with the experimental results from Seabra-Santos et al. (1987). The wave transformation over a continental shelf with different smooth slopes reveals that the solitary wave reflection increases while the continental slope varies from flat to steep. The interaction of the solitary wave with a vertical wall for different wave steepness has been analysed. The reflected shape of the profile is in good agreement with the observation made by Fenton and Rienecker (1982) and an increase in wave celerity is observed.

Marine Geodesy

NWF: Propagation of Tsunami and its Interaction with Continental Shelf and Vertical Wall

Tsunami evolution and run-up in a large scale experimental facility

Journal	Data powered by TypesetCoastal Engineering
Publisher	Data powered by TypesetElsevier B.V.
ISSN	03783839
Open Access	No