Wave Numerical Simulation

This paper proposes a new theoretical model of the nature of the photon that goes beyond the traditional concept of wave-particle duality. The basic hypothesis is that the photon is not a simple entity but has a complex internal structure consisting of "sensitive compressed strings" that act as delicate environmental sensors, responding to ambient changes (such as temperature, vibrations, and electromagnetic fields), and determining based on this whether the photon will exhibit wave or particle behavior. According to this model, the process of observation leads to even subtle effects that act as a catalyst to deconstruct the photons' coherent wave state and convert it into separate particle behavior .
The model proposes an intrinsic mechanism for the collapse and recovery of the quantum state, and reframes the interpretation of quantum superposition as a dynamical process internal to the photon, rather than simply a phenomenon associated with the observing apparatus .

Keywords : Photonic strings, wave-particle duality, observer effect, quantum physics .

Variable speed AC drives are widely used in the industry to adjust the rate of production for better efficiency. Until very recently, such drives were almost exclusively in the domain of DC motors. AC motors feature several advantages over their DC counterparts However, for proper control of the speed of an AC motor, the time ratio between the supply voltage and frequency must be kept constant in order to control slip, where slip is a measure of the magnetic coupling between the rotating magnetic field and the rotor. The aim of this study is to utilize a voltage-controlled oscillator to generate an asymmetric function of voltage and frequency that can keep the slip within acceptable limits under varying operating conditions. The circuit design and analysis were done on a single-phase basis at the component level by numerical methods and simulated for critical performance characteristics using the PSPICE computer simulation software to reveal the true nature of the circuit before it can be implemented on a circuit board. The results were then compared them with those of the most widely used carrier-based Sinusoidal PWM Speed controller to validate it using the PSIM motor control software on a PSIM model of a three-phase Squirrel-Cage motor. The simulation results show that the voltage-controlled oscillator PWM Speed Controller controls twice as much load as the Sinusoidal PWM Speed Controller. In addition, it has no AC to DC-converter and fixed DC link and features a smaller number of active and passive components, which makes it simple and affordable in both size and ease of implementation.

This study investigates the evolution of the Iztuzu beach shoreline and its response to wave storm characteristics and frequencies. Firstly, using the Digital Shoreline Analysis System (DSAS) tool, high spatial resolution satellite imagery, coastal changes were assessed over various time scales covering the decade of 2013-2022. Secondly, considering the same timeframes, wave storm characteristics occurrence and characteristics of Iztuzu beach were assessed. Lastly, the coastal evolution and wave storm assessment results are linked based on correlation analysis to define the relation between the observed coastal changes and the wave storm frequency and characteristics changes. Thus, the present study's main advance lies in considering the impact of some key characteristics of wave storms, such as storm duration, direction and total energy, on shoreline evolution. The correlation analysis of shoreline changes and storm characteristics revealed the influence of wave storms on coastal dynamics. The study results highlight the significant sensitivity of certain beach zones to storm characteristics and point out the possibility of predicting future shoreline changes using projected wave storm patterns. Throughout the study period, Zones II, III, and IV experienced consistent erosion, likely attributable to the interaction between the southwest-oriented shoreline and the prevailing storm wave direction from the South. This alignment generates strong drift currents, contributing to the observed shoreline retreat. For instance, the correlation exceeded 0.8 at Zones III, IV, and V for wave storm duration, SPI and TSWE against the EPR, and 0.7 at the same zones for the same characteristics against the LRR. As a result, coastal erosions at Iztuzu Beach are more linked to the intensity and duration of southern wave storms. Thus, this study emphasizes the importance of combining wave storm data and shoreline analysis to develop effective coastal management and mitigation strategies.

We consider the two-layer moist-convective thermal rotating shallow water equations and design a flux globalization-based, well-balanced, path-conservative central-upwind numerical scheme for the studied model. We use the developed scheme to conduct a series of numerical simulations and report the observation of eastward-propagating excited dipolar systems. These systems are characterized by one or more convectively coupled, poorly isolated dipolar fronts, primarily driven by the equatorial adjustment of large-scale localized positive buoyancy or potential temperature anomalies on the equatorial beta plane. A formation of these dynamic structures is triggered when disturbances exceed a critical threshold in a moist-convective environment. Notably, during the evolution of cyclones, secondary counter-rotating anticyclones develop in the lower layer, while oppositely signed structures emerge in the upper layer, highlighting the system's vertical coupling. A significant finding of our experiments is the identification of a time lag mechanism, observable even under weaker moist-convective conditions, between the initial state and the system reaching the excited threshold required for eastward propagation. This time lag underscores a critical build-up phase, during which the system accumulates the necessary energy and momentum to transition into a dynamically active state.

A two phase Smoothed Particle Hydrodynamics method is developed to simulate the violent deformation of the free surface and the formation of the cavity induced by the two dimensional wedge entering water. The flow field of water and air are computed simultaneously. A non-reflection boundary treatment for SPH method is proposed to remove reflection of pressure wave against the solid boundaries of computational domain. The water jet generated at the early stage of water entry and the cavity induced by the free surface sealing are reproduced for the case of the vertical water entry of a wedge. The computational pressure distribution and the velocity field can be obtained. Numerical results agree well with the experimental data in literature to verify the two phase SPH method and the boundary treatment approach. It turns out that the cavity evolves with significant deformation of the cavity surface.

This study deals with the sea-flood risk in a small lagoon called “Etang de La Palme” on the mediterranean coast of Languedoc (south of France). The risk of a sea-flood in this vulnerable area had been analysed through an integrated approach, combining the ...

Pour caractériser le risque de submersion marine, il est très important d'avoir une connaissance précise des lois de distribution des niveaux d'eau marins, et plus particulièrement des niveaux d'eau extrêmes. En effet ce sont eux qui sont à l'origine des conséquences les plus dramatiques. Le programme de recherche mené au cours de cette thèse a été financé par le Ministère de l'Écologie, du Développement Durable et de l'Énergie. L'objectif final est de fournir des valeurs de référence de niveau d'eau marin le long des côtes françaises, par le biais d'une méthode d'analyse statistique des extrêmes. Ces niveaux comprennent les trois composantes suivantes : la marée, la surcote météorologique et le wave set-up. Le principe de base utilisé est le suivant : une analyse statistique est effectuée aux ports où la donnée marégraphique est disponible, puis le résultat est interpolé entre les ports. Différentes approches sont testées. Les points suivants...

Pour caracteriser le risque de submersion marine, il est tres important d'avoir une connaissance precise des lois de distribution des niveaux d'eau marins, et plus particulierement des niveaux d'eau extremes. En effet ce sont eux qui sont a l'origine des consequences les plus dramatiques. Le programme de recherche mene au cours de cette these a ete finance par le Ministere de l'Ecologie, du Developpement Durable et de l'Energie. L'objectif final est de fournir des valeurs de reference de niveau d'eau marin le long des cotes francaises, par le biais d'une methode d'analyse statistique des extremes. Ces niveaux comprennent les trois composantes suivantes : la maree, la surcote meteorologique et le wave set-up. Le principe de base utilise est le suivant : une analyse statistique est effectuee aux ports ou la donnee maregraphique est disponible, puis le resultat est interpole entre les ports. Differentes approches sont testees. Les points suivants...

This article presents, to the best of our knowledge, a novel simulation model for bacterial adhesion on rough surfaces, combining the SPH method with the LJ potential. A Staphylococcus aureus-like spherical bacterial cell is modeled as a rigid body in a fluid simulated with PySPH. The rough surface is characterized by shear force microscopy (ShFM), with bacteriasurface interactions described by the LJ potential. Surface-fluid interactions are modeled using WCSPH, and bacterial-fluid coupling is addressed through SPH, overcoming limitations of previous models. This model offers a powerful tool for studying bacterial adhesion and surface interactions in fluid environments.

Lagrangian particle-based methods have opened new perspectives for the investigation of complex problems with large free-surface deformation. Some well-known particle-based methods adopted to solve non-linear hydrodynamics problems are the smoothed particle hydrodynamics (SPH) and the moving particle semi-implicit (MPS). Both methods modeled the continuum by a system of Lagrangian particles (points) but adopting distinct approaches for the numerical operators, pressure calculation, and boundary conditions. Despite the ability of the particle-based methods in modeling highly nonlinear hydrodynamics, some shortcomings, such as unstable pressure computation and high computational cost remains. In order to assess the performance of these two methods, the weaklycompressible SPH (WCSPH) parallel solver, DualSPHysics, and an in-house incompressible MPS solver are adopted in this work. Two test cases consisting of threedimensional (3D) dam-break problems are simulated, and wave heights, pressures and forces are compared with available experimental data. The influence of the artificial viscosity on the accuracy of WCSPH is investigated. Computational times of both solvers are also compared. Finally, the relative benefits of the methods for solving free-surface problems are discussed, therefore providing directions of their applicability

Realistic lunar tides of the Great Bay Estuarine System have been simulated using a fixed boundary finite element numerical model as described by . It is a two-dimensional, nonlinear, time-stepping model with a groundwater component coupled to a kinematic force balance to facilitate the realistic drainage and filling of elements during ebb and flood, respectively. The numerical model reproduces the observed M 2 tides as described by , and it successfully captures qualitatively correct residual currents and transports, realistic massconserving flooding and dewatering of the tidal flats, and current asymmetry between flood and ebb. The simulation results were sensitive to local bathymetry and the implemented friction law. The accuracy of the model is demonstrated by comparison with the 1975 Great Bay study in terms of tidal elevations at 14 tidal stations and 4 cross-sectionally averaged current measurements in the estuary. Quantitatively, the model results show good agreement with observations, displaying correlation coefficients of !0.96 in surface elevation and !0.95 in averaged current, with average RMS errors of 0.12 m and 0.26 m s À1 , respectively. In addition, tidal flat hydrodynamics, characteristic distributions of residual current, sediment bed load transport, and influence of topography on the overall circulation in the region are also discussed.

The study of this paper suggests on dependency problem in fuzzy computational method by using the numerical solution of Fuzzy differential equations(FDEs) in Milne's predictor-corrector method. This method is adopted to solve the dependency problem in fuzzy computation. We solve some fuzzy initial value problems to illustrate the theory.

The Rho GTPases pattern the cell cortex in a variety of fundamental cell-morphogenetic processes, including division, wound repair, and locomotion. It has recently become apparent that this patterning arises from the ability of the Rho GTPases to self-organize into static and migrating spots, contractile pulses, and propagating waves in cells from yeasts to mammals.1 These self-organizing Rho GTPase patterns have been explained by a variety of theoretical models that require multiple interacting positive and negative feedback loops. However, it is often difficult, if not impossible, to discriminate between different models simply because the available experimental data do not simultaneously capture the dynamics of multiple molecular concentrations and biomechanical variables at fine spatial and temporal resolution. Specifically, most studies typically provide either the total Rho GTPase signal or the Rho GTPase activity, as reported by various sensors, but not both. Therefore, it remains largely unknown how membrane accumulation of Rho GTPases (i.e., Rho membrane enrichment) is related to Rho activity. Here, we dissect the dynamics of RhoA by simultaneously imaging both total RhoA and active RhoA in propagating waves of Rho activity and F-actin polymerization.2,3,4,5 We find that within nascent waves, accumulation of active RhoA precedes that of total RhoA, and we exploit this finding to distinguish between two popular theoretical models previously used to explain propagating cortical Rho waves.

Dos modelos paramétricos de viento fueron usados para simular la distribución del oleaje en huracanes en uno de los, así llamados, modelos de tercera generación. Se usaron varias condiciones durante huracanes en el Golfo de México y frente a la península de Florida para probar y ajustar los modelos de viento. La información usualmente disponible en las oficinas meteorológicas, como: presión central, radio de viento máximo y las posiciones geográficas, es la única necesaria para crear un perfil de viento con estos modelos paramétricos. Se obtuvieron resultados comparables entre las alturas de olas medidas y las simuladas por el modelo de olas. Esto demuestra la utilidad de estas herramientas para realizar diagnóstico y pronóstico de oleaje durante huracanes en la región. Esta información es valiosa para las entidades gubernamentales como ayuda en la toma de decisiones apropiadas en la eventualidad de presentarse estos fenómenos meteorológicos, los cuales podrían ser más frecuentes e ...

Une base de données numériques d'états de mer en Méditerranée est en cours de construction à partir de simulations effectuées avec le logiciel de TOMAWAC sur la période 1979-2008 afin de venir compléter l'actuelle base de donnée ANEMOC couvrant la façade Atlantique-Manche-Mer du Nord des côtes françaises. Les champs de vent utilisés en entrée sont issus de la réanalyse météorologique NCEP2 du U.S. Climate Diagnostics Center of the National Oceanic and Atmospheric Administration (CDC-NOAA). Les résultats du modèle sont comparés à des mesures de bouées et des mesures satellitaires altimétriques. Les premières comparaisons des résultats de simulations aux mesures montrent un biais moyen négatif (sous-estimation) de la hauteur significative d'état de mer, qu'il convient d'améliorer en travaillant sur les champs de vent et en ajustant les paramètres physiques des termes puits / sources du modèle d'états de mer.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

For the interaction between ocean wave and bottom-mounted structures, it is often required to introduce an artificial interface by which the fluid domain unbounded horizontally is divided into an interior subdomain with finite volume and an exterior one, to focus on the structures and the interior fluid subdomain only. In this paper, an artificial circular cylindrical surface and a novel Dirichlet-to-Neumann (DtN) map on it are suggested to close the constitutive equations in the interior subdomain since the top and bottom faces of the interior subdomain satisfy free surface condition and seabed condition, respectively. The DtN map is used as a boundary condition of the problem for the interior subdomain, which will be solved using the method of boundary integral equation (BIE). Upon successful validation for a bottom-mounted circular cylinder, the present method is extended to the cases of a single rounded-rectangular cylinder and an array of four cylinders mounted on a flat or undulated seabed to obtain three-dimensional wave elevation around them and to study the effects of fillet radius and incident angle on the wave force acting on each cylinder.

Recently, Rim et al. (Wave Motion 116:103063, 2023) proposed an exact Dirichlet-to-Neumann (DtN) boundary condition to study the water wave motion over undulated seabed by wave diffraction. This paper focuses on linear wave interaction with a bottom-mounted body near a vertical wall. The water domain is separated into an exterior subdomain and an interior one by a virtual cylindrical surface or so-called an artificial boundary which encloses not only the original body but also its imaginary one about the vertical wall. The wave interaction with the bodies in the interior subdomain is solved by using a boundary integral equation with an exact DtN operator on the artificial boundary which is derived from a velocity potential in the exterior subdomain. Upon successful verification of the present approach by comparison with the results of ANSYS AQWA for a bottom-mounted vertical circular cylinder near the wall, the model is extended to a vertical cylinder with cross section of rounded rectangle.

The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artificial boundary condition. The artificial boundary is usually selected as a circle or spherical surface to solve various types of fields, such as sound waves or electromagnetic waves, provided that the considered domain is infinite or unbounded in all directions. However, the substantial wave motion is considered in water of finite depth, that is, the fluid domain is bounded vertically but unbounded horizontally. Thus, the DtN boundary condition is given on an artificial cylindrical surface, which divides the water domain into an interior and exterior region. The boundary integral equation is adopted to implement the present model. In the case of a floating cylinder, the results of hydrodynamic coefficients of a chamfer box are discussed.

This paper is concerned with three-dimensional water wave motion over undulated seabed. For the wave motion problem in seawater of finite depth, the fluid domain is usually unbounded horizontally but bounded vertically by free water surface and seabed which have their own boundary conditions. To study local wave motion over undulated region only, a novel Dirichlet-to-Neumann (DtN) boundary condition is suggested on an artificial circular cylindrical surface by which the fluid domain is divided into an interior region with finite volume and an exterior region. A unique solution of wave motion in the interior region is guaranteed by the novel boundary condition on the artificial cylindrical surface and the other boundary conditions on mean free water surface and undulated seabed. The solution is obtained by using Boundary Integral Equation (BIE) with all boundary conditions including the novel artificial boundary condition. Upon verification for a submerged square cylinder, the present model is extended to the case of an array of rounded-rectangular cylinders or circular paraboloidal shoals.

The presence of residual subduction zone under Kuril island arc makes a region of Kuril ridge islands be potential seismic-danger since underwater earthquakes in subduction zone with magnitude М > 6 are usually tsunamigenic. Potential strong earthquakes near the Kuril-Kamchatka trench passes along Kuril island, and tsunami generated by them carry a greater risk while passing through Bussol and Krusenstern straits for all Okhotsk seashore including the Sakhalin coast where now taking place a rising of infrastructure development connected with development an oil and gas industry. In the history, a few occasions of tsunami generation near the Sakhalin coast, caused by earthquakes in Kuril ridge region had been recorded (see, e.g. [1]). Such occasion taken place while strongest earthquake occurs recently near the Simushir island (15 November 2006). This earthquake and tsunami were predicted half of year before the event: while marine expedition clarified structure and size of possible undersea source in the area of seismic gap in Middle Kuril region. Then, the numerical " 1

1 Новосибирский государственный университет 2 Институт автоматики и электрометрии СО РАН 3 Институт вычислительной математики и математической геофизики СО РАН mmlavr@nsu.ru В работе рассматриваются вопросы применения современных компьютерных архитектур для ускорения обработки данных в применении к такой проблеме, как защита прибрежных территорий от разрушительных волн-наводнений цунами. Актуальность темы обусловлена произошедшими в по-следние пятнадцать лет глобальными катастрофами, связанными с подводными землетрясениями и последовавшими за ними волнами цунами. Обсуждаются способы получения данных о волне цунами и способах быстрого компьютерного моделирования с целью оценить основные параметры волны на побережье. В случае сейсмических событий на Японском жёлобе волна цунами достигает ближайшей точки побережья примерно через 20 минут. Следовательно, система предупреждения о цунами должна получить данные, обработать их и выдать прогноз об опасности цунами за меньшее время. Приво-дят...

Current, sea level and bed load transport are investigated in the Great Bay Estuary, New Hampshire, U.S.A.-a well-mixed system with low freshwater flow and having main channel tidal currents over 2 m/sec. Current and sea level forced by the Mi-Mi-Ma tide at the estuary mouth are simulated by a vertically averaged, nonlinear, time-stepping, finite-element model. The hydrodynamic model uses a fixed boundary computation domain and accounts for flooding-dewatering over tidal flats by making use of a groundwater component. Inertia terms are neglected in comparison with pressure gradient and bottom friction terms, which is consistent with the observed principal dynamic balance for this system. The accuracy of the hydrodynamic predictions is demonstrated by comparison with 5 tidal elevation stations and 2 cross-sectional ly averaged current measurements. Simulated current and bottom stress are then used to model bed load transport in the vicinity of a rapidly growing shoal located in the main channel of the lower system. Consisting of coarse sand and gravel, the shoal must be dredged every 5-8 years. Two approaches are taken-an Eulerian parametric method in which nodal bed load flux vectors are calculated at each time step and a Lagrangian particle tracking approach in which a finite number of sediment particles are released and tracked. Both methods yield pathways and accumulations in agreement with the observed shoal formation and the long-term rate of sediment accumulation in the shoal area.

Wave loads are critical factor for the design and safe operation of offshore structures.
The accurate determination of these loads is essential to ensure the structural
reliability and operational efficiency of such platforms at sea. This study develops
analytical expressions for calculating wave loadings that affect the support of various
Condeep-type offshore structures. In this regard, wave load calculations for the
Draugen Monopile Condeep platform, previously constructed in Norway, were
analyzed in the context of a case study. The results of this assessment provide useful
information regarding the characteristics of wave loads and their relevance to the
overall structural analysis. Furthermore, the investigation also covers
recommendations for design and safety improvements that consider the calculated
wave loads and the assessment of the structural reliability. Study is expected to
contribute to the knowledge base surrounding offshore engineering practices and
improve resilience and functionality against dynamic wave forces.

The evaluation and implementation of two public domain wave spectral models: SWAN and WAM to be used in hindcasting and forecasting in the Central American region are presented. The typical model characteristics are analyzed using simulations for simple bathymetric cases. The model responses are evaluated using boundary conditions in the Caribbean region including extreme meteorological conditions like hurricanes. Those natural phenomena's are of great importance given the historical frequency impacts in the region. The SWAN model shows some difficulties to propagate wave energy in big areas generating some wave height and direction anomalies mainly around islands or in low interpolated depth values. The numerical schemes and the different model's variable parameterizations are responsible for the different spatial energy propagation found in some applications in this study. An integrated system could be working for the whole region where the wave information is necessary ...

Un modelo numerLCO espectral bidimensional de segunda generación fue adaptado para pronostico operacional de oleaje en el Mar Caribe. To evaluate the model results the wave height and period were compared with the National Weather Service forecast and with de ocassional ahip reporta.

Fluid simulation using meshless methods has increasingly become a robust way to solve mechanics problems that require dealing with large deformations and has become very popular in many applications such as naval engineering, mechanical engineering, movies, and games. The current challenge is to simulate and render the fluid in real time. This works contributions are: a GPU implementation of the SPH method, which provided an average speedup of 11.55 in comparison to the reference multicore CPU implementation, being able to simulate 1M particles at, approximately, 3 fps; also, a Ray Tracing based rendering solution that can be used to render any particle based fluid simulation method is proposed, which is able to render a large number of particles in interactive rates, for instance, 2M particles at 2.7 fps for a resolution of 1920 x 1920 pixels.

Un des objectifs du projet de recherche EMACOP (Energies MArines, COtières et Portuaires) est de caractériser le potentiel houlomoteur près des structures portuaires et côtières, comme les digues et jetées. L'article présente l'application d'un modèle nonhydrostatique de propagation et de transformation des vagues en proche côtier SWASH pour deux sites exposés de Bretagne. Les simulations numériques sont effectuées avec SWASH pour les conditions de houle dominante et trois niveaux de marée. Les résultats présentés ici permettent de caractériser le potentiel houlomoteur et de définir les zones énergétiques propices à l'installation de systèmes de récupération sur les deux sites.

This paper investigates fluid and floating object interaction using a novel adaption of the Smoothed Particle Hydrodynamics (SPH) method. This problem is significant to reducing the difficulties of cost-effective designs of wave energy converters, offshore and coastal structures. In ...

The dispersion relation of elastic Bloch waves in 1-3 piezoelectric phononic structures (PPnSs) with Langasite (La3Ga5SiO14) inclusions in a polymeric matrix is reported. Langasite presents promising material properties, for instance good temperature behaviour, high piezoelectric coupling, low acoustic loss and high quality factor. Furthermore, Langasite belongs to the point group 32 and has a trigonal structure. Thus, the 2-D bulk wave propagation in periodic systems with Langasite inclusions cannot be decoupled into XY and Z modes. The improved plane wave expansion (IPWE) is used to obtain the dispersion diagram of the bulk Bloch waves in 1-3 PPnSs considering the classical elasticity theory and D3 symmetry. Full band gaps are obtained for a broad range of frequency. The piezoelectricity enhances significantly the band gap widths and opens up a narrow band gap in lower frequencies for a filling fraction of 0.5. This study should be useful for surface acoustic wave (SAW) filter and...

Национальный исследовательский Московский государственный строительный университет, г. Москва, Россия Аннотация. В работе приводится доказательство теоремы существования и единственности аналитического решения класса нелинейных дифференциальных уравнений третьего порядка, правая часть которого представлена полиномом шестой степени, в комплексной области. Расширен класс рассматриваемых уравнений за счет новой замены переменных. Получена априорная оценка аналитического приближенного решения. Представлен вариант численного эксперимента оптимизации априорных оценок с помощью апостериорных. Ключевые слова: существование и единственность, аналитическое решение, нелинейное дифференциальное уравнение, априорная оценка, апостериорная оценка.

В работе приводится доказательство теоремы существования и единственности аналитического решения класса нелинейных дифференциальных уравнений третьего порядка, правая часть которого представлена полиномом шестой степени, в комплексной области. Расширен класс рассматриваемых уравнений за счет новой замены переменных. Получена априорная оценка аналитического приближенного решения. Представлен вариант численного эксперимента оптимизации априорных оценок с помощью апостериорных. The article presents a proof of the theorem of the existence and uniqueness of the analytical solution of the class of nonlinear differential equations of the third order, with a polynomial right-hand side of the sixth degree, in the complex domain. The class of the considered equations has been extended by means of a new change of variables. An a priori estimate of the analytical approximate solution is obtained. A variant of the numerical experiment of optimizing a priori estimates using a posteriori estimates...

The flooding of a damaged ship in waves is a complex process, often coupled with the internal and external liquid motion together with the ship hull motion. Paramount to the operation safety, in order to improve the prediction accuracy of ship motion during the flooding process, the strip theory is applied to study the dynamic response of the damaged ship in beam seas; a smoothed particle hydrodynamics (SPH) model is developed to consider the coupling effects of various factors including internal sloshing of intact cabins and damaged cabins and external waves. The numerical wave tank with a perfectly matched layer absorbing boundary condition is established and validated by the experimental results. The detailed sensitivity study is carried out focusing on the effects of damaged opening sizes, the relative position of opening, and the incident wave and the liquid loading conditions on the dynamic response of the damaged ship in regular beam waves. It is observed that the flooding process was slowed down and interrupted by the water exchanges at the damaged opening due to the dynamic motion. Compared with the opening facing the incident wave, the back one endangered the ship pronouncedly with large amplitude and frequency roll motion. It is also revealed that the liquid tank in the damaged ship imposes a significant influence on its rolling response. It is further demonstrated that the present SPH model is capable of handling the nonlinear phenomenon in a flooding process of a damaged ship.

The present work is focused on the comparative study of two numerical methods, i.e. MPS method and VOF method, for the prediction of sloshing in LNG tank. Numerical simulations are carried out by an inhouse meshless solver MLParticle-SJTU based on improved Moving Particle Semi-Implicit (IMPS) method, and VOF based CFD solver naoe-FOAM-SJTU developed on the open source platform OpenFOAM. Several sloshing conditions with different kinds of tanks are applied to validate the present two numerical methods. The time histories of impact pressure and flow patterns are presented and compared to the experimental data. For the rectangular tank, sway motion with different excitation periods are taken into account to investigate the sloshing performance and validate the two simulation methods. For the membrane-type LNG tank, pitch motion with different excitation periods are simulated. According to the numerical results, the two methods can both predict the impact pressure compared with the expe...

The objective research is the calculation of free-floating
particle displacement trajectory using the Simulating
Waves Nearshore (SWAN) software having as base
unstructured meshes to get the diagram of the study area.
Third-party tools and data were used, such as bathymetry,
wave and tide data from the Global Ensemble Forecast
System-Wave (GEFS-Wave) and data processing using
SWAN. The modelling software and some local
developments were used to generate valid Delaunay
diagrams for the central zone of the Veracruz state,
Mexico. For the configuration of the experiments, we
worked with physics variables of the modelling software
until achieving one that resembled the real conditions of
the area; once the similarity was achieved, it was possible
to run the experiments to obtain the wave height and
frequency and replace the values in the horizontal
displacement equation until obtaining the spaghetti
diagrams that indicate the possible paths of the particles.

Artificial neural networks are a set of tools that are widely used for the information classification. Its expansion within artificial intelligence has been due to its use in the Machine Learning area. A fundamental part of the artificial neural networks algorithm is the so-called activation function, the above because it is the part that triggers the process as a whole and due to its result the neuron/perceptron sends its outputs. Back-propagation activation function of an artificial neural network is also described; this is artificial neural network with a simpler functioning whose adaptation has made it especially attractive to pattern recognition; also, a different algorithm such as Swish is introduced. As part of the pattern recognition study, three wind classifications present on the Mexican Republic Atlantic coast are formed, each group is made up of graphic files referring to meteorological maps with wind indicators in order to feed the network and as new maps are generated,...

Nowadays, the non-destructive evaluation of structural components allows the detection of cracks and other types of flaws with a high resolution. When cracks are involved in mechanical failure events, fracture mechanics provides concepts for lifetime prediction of components when component geometry, material characteristics and load intensity under steady state or impact loading are known. Under fatigue loads additionally material laws have to be observed. Bringing together these disciplines, quantitative non-destructive testing for lifetime prediction is possible. Due to measurement uncertainties related to crack size geometry, material parameters' inherent scatter and load history are not unambiguously assessable. Therefore, statistical distributions are assumed (e. g. Normal or Weibull) and probabilistic fitness for service assessment (FFS) is performed rather than a deterministic one. This concept of combining quantitative non-destructive testing and probabilistic FFS assessment works well for metals. The fracture mechanics analysis under predominantly static loading has at its core the so called Failure Assessment Diagram (FAD). Hereby, an illustrative tool for condition monitoring is supplied which is also accepted in design rules and codes. Software which addresses the criticality of cracks and other flaw types in the shell of cylindrical pressure vessels was developed. The application of the concept of probabilistic fracture mechanics using Monte Carlo simulation is demonstrated for one example from pipelines.

Starting with the damage tolerance design of structures in aerospace applications it became obvious: NDT procedures, utilized according to standards in the regulated area and according to technical reports, guidelines and handbooks in non-regulated applications have to take into account the uncertainties of the techniques which are system features influenced by the type of product to be inspected, as well as its individual design and manufacturing techniques, the type of non-conformity or irregularity to be detected, the type of ND technique selected, the hardware (transducer and system electronics), the software reliability and-the human factor of the inspector or user. All of the influences are summarized in a feature which is called POD-probability of detection. If there is a certain probability for detection, then there is also a PND, a probability for non-detection. As each technical system is not complete and not ideal the indication of a "finding" or an "alarm" by the system can be a real hit but also a false indication, or also called, false alarm. In the same way, in the case of a "calm" system, i.e. no alarm is observed and no finding is indicated, the system answer can be true or false. For each of the four cases the knowledge of the probability has to be known. POD distributions as function of the size of an individual material irregularity are relevant influencing parameters concerning the probability of the failure of a component evaluated according to a failure assessment diagram so far as a probabilistic approach is applied. The contribution introduces into the state of the art of a software development which especially in the future will be applied to evaluate pipeline integrity after performing in-line non-destructive inspections.

This paper gives the overview of the newly developed FITNET Fitness-for-Service (FFS) Procedure within the framework of the European fitness-for-service network-FITNET project. The FITNET project was a four and half years project with the objective of developing and extending the use of FITNET FFS Procedure for welded and non-welded metallic structures throughout Europe. It is partly funded by the European Commission within the fifth framework program and launched at February 2002 (Proposal No.Contract No. GIRT-CT-2001-05071). The network worked with over 50 organisations from sixteen European and three non-European countries representing various industrial sectors and academia. Further information can be found in the FITNET TN website: http://www.eurofitnet.org. The FITNET FFS Procedure provides sets of analysis options and flaw assessment guidelines for engineering structures by aiming to achieve better design principles, support for fabrication of new components and prevention of service failures due to fracture, fatigue, creep and corrosion damages. The FITNET FFS Procedure is developed, validated and processed within the framework of the CEN Workshop Agreement W22 under the guidance of the Italian standardization organization (UNI). Therefore, it aims to become a European (CEN) standard (via CEN Workshop Agreement 22) for assessing the structural significance of postulated or real flaws (cracks, welding defects, and corrosion damage etc.) This procedure can be used to establish the size limits for defects in various engineering structures and can provide substantial cost savings in operating such structures. The use of the FITNET FFS Procedure involves making an assessment of a component containing a defect to ensure its structural integrity for its intended design life or until its next inspection period. The outcome of the assessment of a component in service will be a decision to operate as is, repair, monitor (including re-setting of inspection intervals), or replace. The aim of this paper is to present an overview of the objectives, main features and status of the FITNET FFS Procedure which is prepared in three volumes,

Le littoral tunisien est soumis à une pression croissante, suite au développement socioéconomique et à la gestion peu rationnelle de ce milieu, ce qui a entrainé, en de nombreux endroits, une érosion plus ou moins importante des côtes sableuses. Ce phénomène résulte de la combinaison de divers facteurs, induits à la fois par la nature et par l'homme, avec des modalités différentes dans le temps et dans l'espace. Le littoral de Tabarka-Berkoukech, situé au Nord-Ouest de la Tunisie, n'échappe pas à ce phénomène de dégradation et connaît, par endroits, un recul important de sa ligne de rivage. La connaissance des conditions hydrodynamiques de cette frange littorale, en particulier celles qui sont liées à l'action de la houle, est nécessaire pour apprécier l'état de stabilité de son trait de côte et pour prévoir les moyens de sa protection. Ce travail a pour objectif d'apprécier les phénomènes qui contrôlent la modification des caractéristiques de la houle (hauteur significative, période et direction), lors de sa propagation vers la côte, qui se traduit par une concentration ou par une dissipation d'énergie, ce qui est en faveur d'une érosion ou d'une sédimentation. Pour atteindre cet objectif, une simulation de la propagation de la houle dans la zone côtière de Tabarka-Berkoukech a été faite à l'aide du modèle STWAVE (STeady-state spectral WAVE model), sous l'interface SMS.9.2 (Surface-water-Modeling-System). Les principaux résultats obtenus nous ont permis de déterminer l'effet de la houle et des courants associés sur l'érosion côtière, en identifiant les zones à forte énergie (cap gréseux Borj Arif), où les iso-amplitudes de la houle se resserrent, et celles à faible énergie (plage el corniche), où les iso-amplitudes s'élargissent. Les variations de la hauteur de la houle sont essentiellement causées par le phénomène de réfraction dans l'ensemble de secteur d'étude et, localement, par le phénomène de diffraction lié à la présence de l'île de Tabarka.

This paper presents new experimental and numerical evidence that perforations in a pipe wall result in a low-frequency bandgap within which sound waves rapidly attenuate. These perforations are modelled as an acoustically soft boundary condition on the pipe wall and show that a low frequency bandgap is created from 0 Hz. The upper bound of this bandgap is determined by the dimensions and separation of the perforations. An analytical model based on the transfer matrix method is proposed. This model is validated against numerical predictions for the pipe with varying perforation geometries. A numerical study is undertaken to model the effect of perforations with ideal acoustically soft boundary conditions and surrounded with an air gap. Close agreement is found between the numerical and analytical models. Experimental evidence shows that the width of the bandgap is accurately predicted with the numerical and analytical models.

The paper is devoted to the description of interactive software for the generation of curvilinear structure grids covering two-dimensional one-connected domains of a complicated form. The algorithms for the generation of boundary grids, the initial grids for iterative processes and final grids of elliptic methods are given. The criteria are described which allow one to estimate the quality of grids generated by different methods and automatically to select the best of them. Some examples of grids constructed making use of the described software are given.

In this work, new least-square moving particle semi-implicit (LSMPS) formulations for the modeling of the heat conduction in laser irradiation processes for both thick blocks and thin plates are developed. These new LSMPS formulations guarantee the conservation of the total thermal energy during the heat exchange between particles. The conservation of the thermal energy in the LSMPS method was implemented together with multiresolution techniques for the discretization of the domain with particles of different sizes so that a better characterization of the thermal gradients in the vicinity of the laser beam can be obtained. The simulation of laser irradiation processes for thin plates is still very challenging for particle methods with spherical particles and this is essentially because it is difficult to accommodate a minimum number of particles along the thickness direction without increasing considerably the resolution or the number of particles in the entire plate. In order to overcome this difficulty, a new multiresolution method based on particles with ellipsoidal shapes was also developed for a more efficient modeling of the laser irradiation in thin plates. By conducting the heat conduction simulations, in which the standard LSMPS method can provide accurate temperature distribution and by comparing the results with an analytical solution, it was confirmed that the proposed method is as accurate as the standard LSMPS method. Moreover, the heat conduction with an external heat source, in which the total thermal energy is not conserved by using the standard LSMPS method, was successfully simulated by using the proposed method. The simulations of laser irradiations were also conducted, and the validity of the proposed method has been confirmed by comparing numerical results with experimental data.

Recent advances in the development of Eulerian incompressible smoothed particle hydrodynamics (EISPH), such as highorder convergence and natural coupling with Lagrangian formulations, demonstrate its potential as a meshless alternative to traditional computational fluid dynamics (CFD) methods. This work aims to address one of the major outstanding limitations of EISPH, its relatively high computational cost, by providing an implementation that can be deployed on multiple graphics processing units (GPUs). To this end, a pre-existing multi-GPU version of the open-source Lagrangian weakly-compressible code DualSPHysics is converted to an EISPH formulation and integrated with an open-source multi-GPU multigrid solver (AmgX) to treat the pressure Poisson equation implicitly. The integration of AmgX within DualSPHysics presents a significant challenge, since AmgX is designed for distributed systems and therefore conflicts with the single-node shared memory design of the multi-GPU DualSPHysics code. The present implementation is validated against well-known test cases, showing excellent agreement with benchmark solutions and demonstrating second-order convergence. A detailed profiling and performance testing is also presented to investigate memory consumption and scaling characteristics. The results show approximately 87 %-95 % strong scaling efficiency and 92 %-94 % weak scaling efficiency in both 2D and 3D on up to four GPUs. Large spikes in memory consumption during the initialisation of the linear solver library are found to impede full utilisation of the device memory. Nevertheless, the present implementation is shown to permit problem sizes on the order of 69.3 million (2D) and 20.8 million (3D) particles on four GPUs (128 GB total device memory), which is beyond what has previously been reported for incompressible SPH on GPUs, where the PPE is treated implicitly, and demonstrates its potential as an alternative to traditional CFD methods.

This work focuses on the extension of the semiimplicit SPH scheme [2] to two dimensions for the shallow water equations. The scheme in [2] was first presented at last year’s SPHERIC workshop, following the semi-implicit finite volume and finite difference approach of Casulli [1]. In standard explicit numerical methods, there is often a severe limitation on the time step due to the stability restriction imposed by the CFL condition. To this end, a new semi-implicit SPH scheme is derived, which leads to an unconditionally stable method. The discrete momentum equation is substituted into the discrete continuity equation to obtain a symmetric positive definite linear system for the free surface elevation. The resulting system can be easily solved by a matrix-free conjugate gradient method. Once the new free surface location is known, the velocity at the new time level can be directly computed and the particle positions can subsequently be updated. The method is validated on a smooth inv...

We focus on the use of a meshless numerical method called Smooth Particle Hydrodynamics (SPH), to solve fragmentation issues as Hyper Velocity Impact (HVI) cases. Firstly applied to fluid flow simulations, this method can be extended to the solid dynamics framework. However it suffers from a lack of accuracy when evaluating state variables as the pressure field. And such inaccuracy generally generates non-physical processes (as numerical fragmentation). In the hydrodynamic context, SPH-ALE methods based on Riemann solvers significantly improve this evaluation, but increase the scheme complexity and low-Mach issues are difficult to prevent. We propose an alternative scheme called γ-SPH-ALE, firstly implemented to solve multi-regime barotropic flows, and secondly extended to solid dynamic cases. It relies on the combination of the SPH-ALE formalism and a finite volume stabilizing low-Mach scheme. Its characteristics are detailed and evaluated through a nonlinear stability analysis, hi...

The coastal flood during the tropical cyclone Tauktae, 2021, at Chellanam coast, Kerala, India, has invited wide attention as the wave overtopping severely affected coastal properties and livelihood. We used a combination of WAVEWATCHIII and XBeach to study the coastal inundation during high waves. The effect of low-frequency waves and the rise in the coastal water level due to wave setup caused the inundation at Chellanam, even during low tide with negligible surge height. Wave setup raised the water level at the coast with steep slopes to more than 0.6 m and peaked during low tide, facilitating wave breaking at the nearshore region. The coastal regions adjacent to these steep slopes were subjected to severe inundation. The combined effect of long and short waves over wave setup formed extreme wave runups that flooded inland areas. At gently sloping beaches, the longwave component dominated and overtopped the seawalls and damaged households along the shoreline. The study emphasizes...