Conical Island Research Articles

Scale Effects Investigation in Physical Modeling of Recirculating Shallow Flow Using Large Eddy Simulation Technique

In this study, the Large Eddy Simulation (LES) model in OpenFOAM was used to investigate the scale effects in the physical modeling of recirculating shallow flow at low Froude numbers. A laboratory test of turbulent flow through a submerged conical island with a Reynolds number of 6,210 was selected. The lab prototype was scaled with factors of 3 and 10 for both undistorted and distorted models. Our study employed the Froude similarity as the gravitational force is more dominant than the others (viscous, drag, and cohesion forces). Because the fluid (water) used for the prototype and model is the same, it is impossible to match the Reynolds, Weber, and Froude numbers simultaneously, resulting in the scale effects. For a scale of 1:1, the LES model could simulate the experimental data by appropriately capturing the vortices behind the conical island. For the undistorted models with scales of 3 and 10, the numerical model captured weaker magnitudes of vortices than the 1:1 scale, indicated by the discrepancies in velocity. In fact, the magnitudes of vortices became weaker with the distorted models. We also observed a significant increment in energy loss behind the conical island (where recirculating flows exist) as the scale increased. However, no significant discrepancies in velocity were observed between the results of the 1:1 scale and the scaled models in front of the conical island, where vortices were absent. These results indicate that the scale effects due to the Froude similarity are quite significant provided that recirculating turbulent flow occurs.

Propagation of Solitary Wave Around Conical Island in Level-Set Finite Element Framework

Lee, H., 2021. Propagation of solitary wave around conical island in level-set finite element framework. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 16–20. Coconut Creek (Florida), ISSN 0749-0208. Though the solitary wave is a single wave, it consists of a complex spectrum of frequencies, which enables in-depth analysis and reliable generation both in the laboratory and in the numerical model. For these reasons, solitary waves are known to be a good candidate for the description of waves including tsunamis since they effectively model the important effects of the long wave on the coasts very well. In addition, it is supposed to propagate over constant depth without appreciable changes, allowing for consistent referencing of its offshore or incident wave height. In this study, the level-set scheme, which is combined with the incompressible Navier-Stokes solver based on the fractional step algorithm in the framework of the finite element method, was applied to the modeling of wave propagation and runup on a circular conical island. Unstructured hexahedral meshes were generated for this purpose and MPI (Message Passing Interface) based parallel algorithms were developed to accelerate the computation. The physical behavior of waves are discussed in detail and the numerical results (e.g., runup heights) are compared with the experimental data. The good agreements were observed.

Adaptive third order Adams-Bashforth time integration for extended Boussinesq equations

We develop the third-order adaptive Adams-Bashforth time integration and the second-order finite difference equation for variable time steps. We incorporate these schemes in the Celeris Advent software to discretize and solve the 2D extended Boussinesq equations. This software uses a hybrid finite volume – finite difference scheme and leverages the GPU to solve the equations faster than real-time while concurrently visualizing them. The newly added adaptive scheme significantly improves the robustness of the model while providing faster computational performance. We simulate several benchmarks using the adaptive time stepping scheme of Celeris Advent and demonstrate the capability of the software in modeling wave-breaking, wave runup, irregular waves, and rip currents. Program SummaryProgram title: Celeris Advent (v.1.3.4)CPC Library link to program files:https://doi.org/10.17632/pwsjdsgz89.1Licensing provisions: GNU General Public License 3Programming language: C++, HLSLNature of problem: Celeris Advent started a new paradigm in nearshore wave simulations and enabled researchers and engineers to run a Boussinesq-type model, faster than real-time and in an interactive environment. For simplicity, we assumed a fixed time step in our first implementation of Celeris Advent. This fixed time step often needs to be chosen conservatively such that the model can resolve the most extreme cases during the experiment. In practical simulations, such as simulating coastal fields, the superposition of boundary and initial conditions may cause rare but extreme conditions, requiring a very small time step that is too conservative during most of the simulation.Solution method: We developed adaptive third order Adams-Bashforth time integration to let Celeris Advent solve the extended Boussinesq equations with a variable time step, allowing it to decrease the time step only when necessary. The adaptive equations are presented in a generic format and therefore can be used for solving other equations as well.Additional comments including restrictions and unusual features: The new version of the Celeris Advent with the adaptive time integration runs ∼3 times faster for the standard conical island benchmark, allowing Celeris Advent simulate this benchmark on a 200×200 grid an order of magnitude faster than real-time on a consumer-level gaming laptop. For a field simulation benchmark, with rare but extreme events, the new version runs ∼25 times faster.

Staggered Conservative Scheme for 2-Dimensional Shallow Water Flows

Simulating discontinuous phenomena such as shock waves and wave breaking during wave propagation and run-up has been a challenging task for wave modeller. This requires a robust, accurate, and efficient numerical implementation. In this paper, we propose a two-dimensional numerical model for simulating wave propagation and run-up in shallow areas. We implemented numerically the 2-dimensional Shallow Water Equations (SWE) on a staggered grid by applying the momentum conserving approximation in the advection terms. The numerical model is named MCS-2d. For simulations of wet–dry phenomena and wave run-up, a method called thin layer is used, which is essentially a calculation of the momentum deactivated in dry areas, i.e., locations where the water thickness is less than the specified threshold value. Efficiency and robustness of the scheme are demonstrated by simulations of various benchmark shallow flow tests, including those with complex bathymetry and wave run-up. The accuracy of the scheme in the calculation of the moving shoreline was validated using the analytical solutions of Thacker 1981, N-wave by Carrier et al., 2003, and solitary wave in a sloping bay by Zelt 1986. Laboratory benchmarking was performed by simulation of a solitary wave run-up on a conical island, as well as a simulation of the Monai Valley case. Here, the embedded-influxing method is used to generate an appropriate wave influx for these simulations. Simulation results were compared favorably to the analytical and experimental data. Good agreement was reached with regard to wave signals and the calculation of moving shoreline. These observations suggest that the MCS method is appropriate for simulations of varying shallow water flow.

Two-phase flow simulation of breaking solitary waves over surface-piercing and submerged conical structures

A two-phase flow model is employed to study three-dimensional (3D) breaking of solitary waves over surface-piercing and submerged conical structures. Details of the wave pre-breaking, overturning, and post-breaking processes are included. The governing equations are discretized by the finite volume method and the PISO algorithm is utilized for the pressure-velocity coupling. The air–water interface is captured using a volume of fluid approach and the Cartesian cut-cell method is implemented to deal with the complex topography of the conical structures. The method is validated first using available experimental data of a solitary wave propagating over a surface-piercing conical island and good agreement between the experiment and simulation data is obtained. The model is then applied to study 3D breaking waves over a submerged conical structure, with 3D wave profiles and surface velocities being presented and discussed. The detailed 3D velocity fields, energy dissipation and transformation during the wave breaking process are presented.

A modal decomposition method for the analysis of long waves amplification at coastal areas

This paper presents a model for the evaluation of long waves amplification at coastal areas, based on a modal decomposition method. It is able of modelling the growth and the decay of the natural modes of the area under investigation, and their contribution to the total wave field. The model is an improvement of that developed by Bellotti et al. (2012b), that was able of calculating the frequencies and the shapes of the natural modes, but not their amplification under the action of forcing waves.Three test cases are used for the validation and to show the capabilities of the model. The first considers the long waves resonance into a long and narrow harbour/bay over a constant water depth. It is a case for which a high degree of wave trapping into the semi-enclosed coastal area is induced by the specific shape of the coastline. The second test deals with the propagation of a group of edge waves along a straight coast with a constant sloping bottom, generated in proximity of the shoreline by a special wave maker. The model in this case properly evaluates what are the edge waves modes that contribute to the total wave field. The third case involves the interaction of a solitary wave with a conical island, for which laboratory data are available. In this test a low degree of trapping exists, but it is interesting for the present aims as the propagation of the waves around the island is expected to occur under the form of wave modes partially trapped by the bathymetry i.e. edge waves, excited by the transient wave arriving from offshore. On the basis of the tests results it is shown what is the role of the more relevant natural modes in the formation of the total surface elevation.

An analytical investigation of oscillations within a circular harbor over a Conical Island

Based on the linearized long-wave equation, an analytical solution for wave oscillations within a circular harbor of constant depth over a conical island is obtained. The analysis divides the study domain into three regions: region I (within the harbor), region II (over the island) and region III (from the island toe to the deep sea). In region I, the water depth is uniform, and the method of separation of variables is used to find the free-surface elevation solution. In Region II, the water depth linearly varies along the radial direction of the island, and the method of separation of variables is adopted again to reveal the free-surface elevation solution expressed in Bessel and Hankel functions. Waves in region III consist of the incident waves and the scattered waves from the island, which are respectively expressed with a Fourier-cosine series and a sum series of Hankel function. The final solution is obtained by matching the free-surface elevation and its normal derivatives at the interfaces between the three regions. To confirm the validity of the analytical solution, via adjusting topographical parameters, it was further utilized to compare with the existing analytical solutions for wave-induced oscillations in a circular harbor of constant depth and the scattering of long waves around a cylindrical island mounted on a conical shoal. Finally, as the topographical features of Maug Islands resembles the geometry studied in this article, the coupled oscillation characteristics for Maug Islands are examined. The existence of the island does aggravate oscillations within the harbor, and the features are addressed in details.

A topoclimate model for Quaternary insular speciation

AbstractAimUnderstanding the drivers of speciation within islands is key to explain the high levels of invertebrate diversification and endemism often observed within islands. Here, we propose an insular topoclimate model for Quaternary diversification (ITQD), and test the general prediction that, within a radially eroded conical island, glacial climate conditions facilitate the divergence of populations within species across valleys.LocationGran Canaria, Canary Islands.TaxonThe Laparocerus tessellatus beetle species complex (Coleoptera, Curculionidae).MethodsWe characterize individual‐level genomic relationships using single nucleotide polymorphisms produced by double‐digest restriction site associated DNA sequencing (ddRAD‐seq). A range of parameter values were explored in order to filter our data. We assess individual relatedness, species boundaries, demographic history and spatial patterns of connectivity.ResultsThe total number of ddRAD‐seq loci per sample ranges from 4,576 to 512, with 11.12% and 4.84% of missing data respectively, depending on the filtering parameter combination. We consistently infer four genetically distinct ancestral populations and two presumed cases of admixture, one of which is largely restricted to high altitudes. Bayes factor delimitation support the hypothesis of four species, which is consistent with the four inferred ancestral gene pools. Landscape resistance analyses identified genomic relatedness among individuals in two out of the four inferred species to be best explained by annual precipitation during the last glacial maximum rather than geographic distance.Main conclusionsOur data reveal a complex speciation history involving population isolation and admixture, with broad support for the ITQD model here proposed. We suggest that further studies are needed to test the generality of our model, and enrich our understanding of the evolutionary process in island invertebrates. Our results demonstrate the power of ddRAD‐seq data to provide a detailed understanding of the temporal and spatial dynamics of insular biodiversity.

Staggered Scheme for Shallow Water Equations with Quadtree-subgrid

To get accurate results, high-resolution numerical simulations are often required. However, computation using high resolution grid often require larger computer memory and longer computational time. One way to overcome this problem is by adopting a scheme that can handle a non-homogeneous grid; i.e. a computational domain with two or more resolutions. In this work, a two-level quadtree-subgrid method was applied. It uses a combination of structured grid with hierarchical quadtree ordering. This method is applied on a staggered grid scheme for the two-dimensional shallow water equations. A benchmark simulation of wave run-up on a conical island was conducted for validation. Comparison between computing time of simulations using the fine grid and the quadtree-subgrid shows the effectiveness of this quadtree-subgrid scheme.

Seismic Observation of Tsunami at Island Broadband Stations

AbstractPrevious studies have reported seismic observations of tsunami recorded at island broadband stations. Coastal loading by the tsunami can explain them. For further quantification, we model tsunami propagation assuming an axisymmetric structure: a conical island with a flat ocean floor. The total tsunami wavefield can be represented by superposition between an incident tsunami wave and the scattering. The ground deformation due to the total tsunami wavefield at the center is calculated using static Green's functions for elastic half‐space with a first‐order correction for bathymetry. By fitting the modeled displacement to observed seismic data, we can infer the incident tsunami wave, which can be interpreted as the virtual tsunami amplitude without the conical island. First, we apply this new method to three components of seismic data at a volcano island, Aogashima, for the 2015 Torishima‐Oki tsunami earthquake. The estimated tsunami amplitude from the vertical component is consistent with the offshore array observation of absolute pressure gauges close to the island (1.5–20 mHz). The estimated incident azimuth from the three components is also consistent with ray theory. Second, we apply this method to seismic data at four island broadband stations in the Indian ocean for the 2010 Mentawai tsunami earthquake in Indonesia. Despite the limited observed frequency range from 0.5–2.0 mHz, the amplitudes and incident azimuths are consistent with past studies. These observations can complement offshore tsunami observations. Moreover, this method is applicable not only for a tsunami but also for background ocean infragravity wave activity.

Simulation on tsunami-like solitary wave run-up around a conical island using a modified mass source method

Predicting the maximum run-up height and inundated area caused by tsunami events has been a hotly debated topic recently. Nevertheless, the wave height-to-depth ratios (nonlinearity) adapted previously tended to be conservative, considering the fact that a tsunami wave is an extreme wave condition with large wave height. In the present study, a mass source wave-generating approach for highly nonlinear waves is presented using our in-house solver, DUT-FOAM, which is a hydrodynamic solver developed using the open source code library OpenFOAM. By fully considering the mass output from the source region, a more reasonable mass source function has been obtained to compensate for the inadequacy of original method in simulating highly nonlinear waves. A newly designed numerical wave tank is performed for different nonlinearities. Numerical simulations of tsunami wave propagating to a conical island are carried. Fairly good agreements are obtained from the qualitative and quantitative comparisons between numerical results (Liu, Cho, Briggs, Kanoglu, & Synolakis, 1995) and laboratory data (Briggs, Synolakis, Harkins, & Green, 1995) regarding run-up maps around the island. The comparison reveals that present model offers a fast and accurate way to simulate highly nonlinear waves and is potentially useful and efficient for forecasting the run-up heights.

EMPIRICAL AND NUMERICAL MODAL ANALYSIS OF COASTAL AREAS PRONE TO TSUNAMI RISK

In this paper the Empirical Orthogonal Function (EOF) method and the k-f spectral technique are applied to extract from experimental data related to landslide-tsunamis propagating around the coast of a conical island, the wave modes that contribute to the wave field. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It is shown that it is possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important.

A 2DH hybrid Boussinesq-NSWE solver for near-shore hydrodynamics

This paper presents a numerical model that simulates the nearshore circulation and the propagation of waves in two horizontal dimensions (2DH) across the coastal zone, from intermediate depth to zero depth. Pre-breaking, wave propagation is calculated using a Boussinesq equation set with enhanced dispersion characteristics, discretised using second-order central differences and solved using the conjugate gradient method with fourth order Runge-Kutta time integration. In the breaker zone, the Boussinesq dispersive terms are gradually switched off, and the resulting non-linear shallow water equations solved using a finite volume MUSCL-Hancock scheme with an HLLC approximate Riemann solver. Broken waves are treated as hydraulic bores. A wetting and drying algorithm models the moving wet/dry front at the shore. Waves are generated by a line of independently moving piston paddles which are represented through a linear mapping, stretching and compressing the grid in the region of the paddles. Model verification tests include wave sloshing in a frictionless basin, seiching in a parabolic basin with bed friction, solitary wave propagation over a horizontal bed, and the interaction of a solitary wave with a conical island. After calibration, the model simulates the generation of wave-induced currents by regular waves as they interact with sinusoidal and tricuspate beaches, and the propagation of a uni-directional focused wave group over a plane beach. Results are compared against previously published laboratory data. The validation tests confirm that the 2DH model reproduces several important coastal hydrodynamic phenomena including wave-induced currents and multi-component wave packets. The model can thus be used to replicate wave basin experiments, and could be extended to multi-directional waves, leading to a better understanding of hydrodynamic processes in shallow coastal waters.

Large-eddy simulation of shallow turbulent wakes behind a conical island

Large-Eddy Simulations (LESs) and experiments were employed to study the influence of water depth on the hydrodynamics in the wake of a conical island for emergent, shallow, and deeply submerged conditions. The Reynolds numbers based on the island’s base diameter for these conditions range from 6500 to 8125. LES results from the two shallower conditions were validated against experimental measurements from an open channel flume and captured the characteristic flow structures around the cone, including the attached recirculation region, vortex shedding, and separated shear layers. The wake was impacted by the transition from emergent to shallow submerged flow conditions with more subtle changes in time-averaged velocity and instantaneous flow structures when the submergence increases further. Despite differences in the breakdown of the separated shear layers, vortex shedding, and the upward flow region on the leeward face (once the cone’s apex is submerged), similar flow structures to cylinder flow were observed. These include an arch vortex tilted in the downstream direction and von Karman vortices in the far-wake. Spectra of velocity time series and the drag coefficient indicated that the vortex shedding was constrained by the overtopping flow layer, and thus the shedding frequency decreased as the cone’s apex became submerged. Finally, the generalised flow structures in the wake of a submerged conical body are outlined.

Wavenumber-frequency analysis of landslide-generated tsunamis at a conical island. Part II: EOF and modal analysis

In this paper the Empirical Orthogonal Function (EOF) method is applied to extract from the experimental data, related to landslide-tsunamis around the coast of a conical island, the spatial modes that contribute to the wave field. For each mode the wavenumber and the frequency are calculated by analyzing the shape along the coast and the time function. The relevant modes are then compared with those obtained through numerical eigenanalysis of the long wave equation around the considered island. It was possible to associate each EOF mode with some eigenvectors and the corresponding eigenfrequencies, both on the basis of the spatial shape, the wavenumber calculated along the coast and the frequency. Results confirm that landslide-generated waves propagate along the coast as trapped edge waves and the zero-th order mode is the most important. Further of exploring the physics, it is believed that this paper can be of use as some of the most relevant and straightforward techniques for modal identification are applied to the same problem and dataset.

Runup of granular landslide‐generated tsunamis on planar coasts and conical islands

AbstractLarge‐scale physical model experiments of tsunamis generated by granular landslides and volcanic flank collapses are conducted to study the wave runup on both the hill slope laterally adjacent to the landslide and an opposing hill slope. A pneumatic landslide tsunami generator was deployed on planar and convex conical hill slopes to simulate deformable landslides with various geometries and kinematics. On the landslide hill slope, maximum runup and rundown were observed in the landslide impact region followed by adjacent second maxima after the lateral waves were fully formed. The runup and rundown decayed asymptotically from the second maxima. In the conical island scenario, a localized runup amplification was measured on the lee side of the island. Outside the landslide impact region, the effects of the landslide granulometry on the lateral wave runup are minimal. The lateral wave runup on the planar hill slope was generally larger than on the convex conical hill slope outside the landslide impact region. The convex conical hill slope traps less lateral wave energy. The zeroth mode of the edge wave dispersion relation matched the first and second lateral waves on the planar hill slope and the first wave on the convex conical hill slope. Predictive equations for the laterally propagating wave characteristics are derived and a method to predict the runup on an opposing hill slope is presented. The predictive wave and runup equations are benchmarked against the 2007 landslide‐generated tsunami in Chehalis Lake, British Columbia, Canada.

3D PHYSICAL MODELING OF TSUNAMIS GENERATED BY SUBMERGED LANDSLIDES AT A CONICAL ISLAND: THE ROLE OF INITIAL ACCELERATION

This paper presents a new set of 3D experiments aimed to gain insight on the role of the initial acceleration upon the generation process of tsunamis by submerged landslides that may occur at the flanks of conical islands. The
 experiments have been carried out in a large wave tank by varying the initial acceleration of the landslide model. A novel system, relying on the use of a computer controlled stepped motor, has been employed to control the motion of the landslide model. The experiments have been carried out in a parametric way by changing the initial acceleration of the landslide, aiming to reproduce dierent triggering mechanisms. Preliminary experimental findings confirmed the crucial role of the initial acceleration of the submerged landslide in generating tsunamis.

Preface: Thematic issue “Landslide-generated tsunami waves”

Landslide-generated tsunami waves (LGTWs) are gravity waves generated by impulsive impacts of the submarine or subaerial landslides into a water body. Large-scale LGTWs are extreme natural hazards with devastating and fatal consequences on infrastructures and communities. The study of LGTW processes, e.g. slides initiation (or triggering), motion, interaction with water and air, impulsive wave generation, propagation, run-up, overtopping, and inundation, is a multidisciplinary challenge and is an essential task to acquire an informed assessment and to manage the LGTW risks. Landslide-generated waves and the interactions between landslide and water body are the topics of this thematic issue of Landslides. The objective of this issue is to increase awareness and to extend knowledge, about this important theme, among the Landslides readers, both practitioners and researchers. Laboratory experiments are an indispensable component of obtaining a comprehensive understanding of the LGTW event complexities. Alessandro Romano, Marcello Di Risio, Giorgio Bellotti, Matteo Molfetta, Leonardo Damiani and Paolo De Girolamo provide a dataset of three-dimensional experiments for subaerial LGTWs triggered by slide at the edge of a conical island. The high spatial resolution of the dataset can be used for the benchmarking of analytical and numerical models. A series of experimental data in a wave basin with flexible mesh-packed slides is presented by Frederic Evers and Willi Hager. They examine the existing prediction methods for wave height in comparison with the test data. Modelling the interactions of the landslide and water body is a demanding and an elegant task and it is required for an intuitive understanding of the related phenomena and the risk assessment of LGTWs. There are two review articles in this issue with the focuses on the analytical and numerical modelling of LGTWs. An extensive review of the conceptual, mathematical and numerical aspects of the landslide-generated waves modelling for both submarine and subaerial is presented by Saeedeh Yavari-Ramsheh and Behzad Ataie-Ashtiani. They also scrutinise the shortcomings and the future challenges for the numerical modelling of LGTWs. Emiliano Renzi and Paolo Sammarco provide an overview of analytical models for the dynamics of landslide tsunami generation and propagation along beaches and around islands. The analytical modelling is in the framework of shallow-water wave theory. They also suggest directions for the future research of analytical modelling in this field. The application of numerical modelling in association with field measurements and investigations of recent events and case studies, as well as data analysis of historic events are key sources for an enhanced insight into the landslide-generated wave impacts. James Kirby, Fengyan Shi, Dmitry Nicolsky and Shubhra Misra present the numerical simulations for tsunami waves generated by the 27 April 1975 Kitimat, British Columbia submarine landslide. Slide motion is modelled using two approaches by assuming a solid sliding mass or a highly viscous Newtonian fluid lower layer. They show both approaches can resemble the observations. Kyoji Sassa, Khang Dang, Hideaki Yanagisawa and Bin He introduce a new model for the numerical simulation of the landslide-induced tsunami. The underwater landslide initiation and motion, as well as tsunami wave due to the landslide, are simulated. They applied the model to the largest landslide-induced tsunami disaster occurred in Japan and their numerical simulations successfully reproduce the historical tsunami heights, recorded for the 1792 Unzen-Mayuyama event. Sylfest Glimsdal, Jean-Sebastien L’Heureux, Carl B. Harbitz and Finn Lovholt present the results of the post-tsunami field survey and the numerical modelling of the 29th January 2014 submarine landslide at Statland, Norway. By comparing the simulated tsunami run-up for different scenarios with observations, they reconstruct the landslide dynamics, tsunami generation and wave runup. James Goff and James Terry discuss tsunamigenic slope failures as a possible source of the tsunami hazard for Pacific Island Countries and Territories. They suggest a range of indicators such as geological, oral tradition and archaeological components to identify evidence of past tsunamis. Jersain Gomez, Moises Berezowsky, Alejandro Lara and Elizabeth Gonzalez present a study of the water waves generated due a possible semi-submerged landslide in La Yesca Reservoir, Mexico. A physical model of the reservoir and numerical model based on shallow water equations are employed. The Guest Editor hopes that the thematic issue encourages further researches and publications in Landslides on various aspects of LGTW hazards including; warning procedures, understanding of related phenomena, and mitigation measures. I gratefully acknowledge the international experts who reviewed the manuscripts and in particular the support of Editor-in-Chief Professor Kyoji Sassa that made the publication of this thematic issue possible.

Large-scale solitary wave simulation with implicit incompressible SPH

Simultaneously tackling a large-scale simulation domain, high resolution, and a high level of incompressibility presents a computational challenge for smoothed-particle hydrodynamics. We present a method involving a combination of a recently developed implicit incompressible SPH scheme, a fluid-rigid boundary handling technique, and a data structure for neighborhood search to address the problem. We implemented the method on multi-core CPUs and performed simulations of tsunami wave impacts on coastal nuclear facilities to advance the state of the practice in probabilistic risk analysis modeling. Preliminary validation was conducted on a dam break problem test and a solitary wave past a conical island test. In addition to reduced memory consumption and the ability to handle arbitrarily large simulation domains, the technique exhibits fast simulation times. Performance of the method is evaluated for different parameter values related to time-stepping and neighborhood search, and several levels of resolution and incompressiblity enforcement. The results demonstrate its applicability for large-scale simulations relevant to ocean and coastal engineering, and, thereby, as a valuable tool for risk-informed decision-making related to external flooding events.

Tsunamis generated by landslides at the coast of conical islands: experimental benchmark dataset for mathematical model validation

This paper presents a new experimental campaign aimed at reproducing tsunamis generated by landslides at the flank of conical islands. In order to describe in high details the wave field around the island a special acquisition system, which consists of both fixed and movable wave gauges, has been employed. Indeed, each experiment has been repeated several times by changing the configuration of the movable gauges, then obtaining a single virtual experiment with high spatial resolution measurements. Fixed run-up gauges measure the waves at fixed locations to statistically quantify the repeatability of the experiments. Selected experimental results are illustrated within the paper that is mainly aimed at defining a benchmark dataset, available on request, for the development/calibration/validation of analytical and numerical models of tsunamis generated by landslides.