Model Wave Research Articles

Ocean Wave Energy Potential in Southern Waters of Malang

Ocean or marine energy has immense renewable energy capability, able to provide more than double the world’s current electricity consumption. Ocean energy is considered a non-polluting, renewable source of energy. The research was conducted in the waters of South Malang, East Java Province. This research utilizes wave modeling data that has been picture confirmed and processed within one year, in 2022. This procedure will yield the monthly height, period, and direction of wave arrival. The data used to create a map of the location of wave energy in South Malang comes from previously created wave energy maps. This location map is the result of an overlay of multiple prior maps in order to create a site that can be developed for the usage of wave energy. According to the results, the southern locations of Donomulyo, Bantur, and Sumbermanjing have the most potential for using wave energy for buoy planting. Point 29 is the closest point following point 30 to point 34. However, point 29 is the area covered by the turtle migratory route. Point 34 is the farthest away from the other two places if the distance from the coastline to the potential point is calculated perpendicularly. Despite its distance from the coast, this site experiences the least disturbance when compared to others.

Full wave modeling of radio-frequency beams in tokamaks in the electron cyclotron frequency range

Simulation of full wave, without paraxial approximation, high-resolution solution of wave equations in frequency domain in the electron cyclotron resonance (ECR) frequency range for realistic Tokamak plasma parameters became possible by using recently formulated hybrid iterative algorithm [Svidzinski et al., Phys. Plasmas 25, 082509 (2018)] for numerically solving discretized wave equations. This approach combines time evolution and iterative relaxation techniques into iteration cycles. This algorithm is implemented in 2D code FullWave, solving wave equations in Tokamaks in cold and hot plasma models, and it has been tested in 3D full wave iterative RF beams simulation tool, which is presently being developed to model 3D ECRH RF beams in fusion devices using dynamic grid adaptation. The results of 2D full wave modeling, assuming specified toroidal mode number, of ECRH RF beams in DIII-D plasma, performed in the cold and hot plasma models for outboard and top launch scenarios using FullWave are presented. Nonlocal hot plasma response model, based on accurate numerical solution of linearized Vlasov equation, is used to model beam propagation and absorption in the 2nd electron cyclotron harmonic region. Demonstration of capability of the hybrid iterative algorithm to model ECRH RF beams in 3D is made by simulating a substantial part of realistic beam in DIII-D, launched from outboard side of the machine. All relevant physics of RF beam propagation, most of which is not captured in paraxial approximation, such as beam's divergence, interference between the X and O modes in the beam, X-O mode conversion, beam splitting into the X and O mode beams, transformation of beam's cross section, and absorption at the 2nd electron cyclotron harmonic, is captured in the simulations. A numerical technique to find an optimal beam polarization at the launcher to launch a nearly pure X or O mode beam in plasma is developed and tested.

Spatial trend analysis of significant wave heights in the Kara Sea

Over the past decades, the extent of sea ice in the Arctic, including the Kara Sea, has been diminishing. This phenomenon has a direct impact on wind waves as the increased expansion of ice-free water influences wave height. Furthermore, alterations in the ice cover also lead to modifications in atmospheric circulation, necessitating a concurrent analysis of wind and waves to refine the understanding of their interrelationships. In this study, wave modeling data were employed using the WAVEWATCH III model and NCEP/CFSR/CFSv2 reanalyzes. Calculations were performed on a non-structural computational grid. The grid covers the Barents and Kara Seas, as well as the entire northern part of the Atlantic Ocean. The spatial resolution varies from ~ 700 m for the coastal zone of the Kara Sea, to ~ 20 km in the open part of the Kara Sea, covering the period from January 1, 1979 to December 31, 2021. Subsequently, average significant wave heights (SWH), maximum SWH, and the 95th percentile of SWH were computed for each grid node on both monthly and yearly basis. The annual values were analyzed for trends and their significance. Calculations were conducted for both the entire period and ice-free period. Positive trends in annual mean values were observed throughout the sea, with the maximum trend occurring near the boundary with the Barents Sea, barely exceeding 0.2 m/10 years. The northern and northeastern parts of the sea were characterized by significant positive trends of the maximum SWH values. Maximum trend values for the 95th percentile of SWH were also evident in the northern part of the Kara Sea. For the ice-free period, maximum trend values were notable for both the annual mean and the 95th percentile of SWH in the northern part of the sea (maximum trend values are approximately 0.25 m/10 years and 0.5 m/10 years, respectively). Significant positive trends in the annual mean SWH were characteristic of the southern part of the sea, while the largest and significant trends for maximum wave heights were observed in the northeast. The assessment of the contribution of wind and ice regimes to the variability of wind waves remains a subject of discussion.

ECMWF and UK Met Office Offshore Blowing Winds: Impact of Horizontal Resolution and Coastal Orography

AbstractWe analyze the performance of the European Centre for Medium‐Range Weather Forecasts (ECMWF) and UK Met Office (UKMO) meteorological models in predicting offshore blowing wind in coastal areas. Our attention is mainly on the Mediterranean coast, up to 200 km distance from the shore. We compare forecast neutral winds with Advanced Scatterometer measurements. The results indicate that the ECMWF forecasts systematically underestimate wind speed with respect to scatterometer data, while the UKMO model tends to overestimate. A cross‐analysis suggests that, better than fetch, model biases are a function of the model horizontal discretization, hence of the number of grid steps the wind runs over the sea. The steepness and roughness of the land orography before entering the sea, together with the related drag parameters, appear to have a strong role in determining the coastal offshore wind values. Surface drag over land tends to reduce the related wind speed, and it takes a few grid points to adjust to the smooth sea surface conditions. This is supported by a detailed study with a high resolution grid, but different orography resolutions. In these simulations, practically identical coastal wind speed distributions are found when the subgrid orography schemes are switched off. Vertical cross‐sections of potential temperature and wind in bora and mistral conditions illustrate the strong role of gravity waves, wind channeling and turbulent diffusion in coastal numerical weather prediction. Besides local wave modeling, this may be relevant for offshore wind farms, typically situated within 5–50 km from the coast.

An analysis of the expected wave conditions in the Mediterranean Sea in the context of global warming

The main objective of the work proposed herewith is to assess the climate change impact on sea state conditions in the Mediterranean Sea under Representative Concentration Pathways and Shared Socio-economic Pathways scenarios and its expected dynamics in the near future. To perform this, the analysis is structured in two-time intervals, each one covering 30 years. The first period represents the recent past, while the second comprises the near future (2041–2070) under the RCP8.5 and SSP5-8.5 scenarios. A wave modelling system based on the SWAN (Simulating WAves Nearshore) model is implemented and validated in the target area using ERA5 wind data to drive the wave model for the recent past. Then, for the same period, simulations with the wave modelling system forced by the Regional Climate Model wind fields are carried out. For the near future, wind fields under the above-mentioned scenarios are considered to drive the wave model. Various analyses and comparisons are performed to identify the climate change impacts on the wave climate and wave power, to evaluate the differences between the results obtained for each scenario, and also the evolution of the characteristics of the extreme values in the Mediterranean Sea basin. No high differences between the average values of significant wave height and wave power obtained under the two scenarios along the entire basin of the Mediterranean Sea were found. In the marginal seas sometimes different trends appear, especially in the Aegean and Tyrrhenian Seas. Regarding the 99th percentile of Hs, under the SSP5-8.5 scenario, they are slightly higher than those under the RCP8.5 scenario.

Mine seismic source location via forward modeling of spherical waves in a multilayered horizontal or inclined medium

Seismic source location is a classic inverse problem in seismology. In mathematical physics, inverse problems have multiple natural solutions. The objective of this study was to develop a generic theory and method of seeking the true solution from multiple solutions for the location of a coal mine seismic source in an idealized velocity structure model of a coal mine with a small scale and complex geological environment. Starting from the simplest velocity structure model, the complexity of the model gradually increased, until it approached the real velocity structure model, i.e., the multilayered horizontal and inclined velocity structure model, in order to find a generic method for solving the multi-solution inverse problem of coal mine seismic source location. Specifically, the wavefront distribution equation in a two-layer horizontal medium was derived and then expanded to any multi-layer horizontal medium. Based on this equation, a positive definite nonlinear equation system was established from the perspective of any observation system. The equation system contained four unknown variables of the spatiotemporal position of the seismic source. To determine the spatiotemporal parameters of the seismic source, nonlinear equations for four stations were required. To solve the nonlinear equation system, an initial iteration value was determined. In order to reduce the difficulty of determining the initial iteration value, the variable substitution method was used to reduce the number of location parameters. By rotating the original geodetic coordinate system of the station to be parallel and orthogonal to the medium interface, the wavefront method was extended to inclined medium. In conclusion, in this study, the problem of coal mine seismic source location in a multi-layer horizontal or inclined medium was effectively solved. The method proposed in this study provides a reference for solving the true solution from multiple solutions for the location of a coal mine seismic source in small-scale coal mines with complex geological environments.

Enhanced wave modeling & optimal plane-wave destruction (OPWD) method for diffraction separation and imaging

One of the primary challenges faced in seismic exploration is to determine the methodology for analyzing the dispersive wave in various models while maintaining the wave's stability at a low-rank one-step approximation. An optimal signal-to-noise ratio can be achieved by utilizing time-stepping in a low-rank one-step wave extrapolation. It is important to note that the ideal time step should be complex valued. Preserving subsurface diffractions can be quite challenging and demands careful monitoring. To tackle this challenge, we suggest implementing the optimal plane-wave destruction (OPWD) method. To ensure the stability of wave propagation, a fundamental three-layer velocity model is calculated at various time intervals. Afterward, a practical model is used to monitor the movement of the mentioned model. The model being discussed includes a syncline, anticline, distinct edges, and a fault with a steep dip angle. The model is evaluated for the process of simultaneous stepping and marching. Based on the research findings, it is evident that there are variations in the time-stepping between the simple and complex models. These differences align with the Nyquist limit of the sampling interval, as expected. Extending the model beyond the Nyquist limit can cause fluctuations in its stability. OPWD achieved excellent results in diffraction separation and high-resolution imaging on both the synthetic data and real data. The synthetic data included a complex model with anticlines, synclines, sharp edges, and deeper faults. The real data was obtained from the Gulf of Mexico, specifically the Walker Ridges line no. 331. The results suggest that the OPWD method is successful in preserving diffraction in both simulated and actual subsurface environments.

Nonlinear modeling of wave–structure interaction for a flexible floating structure

We present a coupled high-fidelity numerical approach for accurately modeling the fully nonlinear wave–structure interaction of a floating highly-flexible structure in waves. The methodology combines numerical methods that solve the Navier–Stokes equations for viscous-flow dynamics with a free surface, and formulates the nonlinear dynamics of the flexible floating structure as a set of differential–algebraic equations. A verification study was conducted for numerical wave generation and propagation, and the discretization error was quantified. The validation was performed against experimental measurements of a flexible structure subjected to regular waves, where its upstream edge was constrained to the vertical equilibrium location. Our comparisons with the experimental data showed a favorable agreement. This study specifically focused on comparing the wave-driven hydroelasticity of a constrained and a freely floating flexible structures. It provided insights into the effects of rigid body motions on its structural deformations in waves. Developed as an open-source tool, our study demonstrates the potential of the coupled methodology for accurately modeling the wave–structure interactions of flexible floating structures in various nonlinear sea states.

Three-Dimensional Simulations of Subaerial Landslide-Generated Waves: Comparing OpenFOAM and FLOW-3D HYDRO Models

AbstractThe recent destructive landslide tsunamis, such as the 2018 Anak Krakatau event, were fresh reminders for developing validated three-dimensional numerical tools to accurately model landslide tsunamis and to predict their hazards. In this study, we perform Three-dimensional physical modelling of waves generated by subaerial solid-block landslides, and use the data to validate two numerical models: the commercial software FLOW-3D HYDRO and the open-source OpenFOAM package. These models are key representatives of the primary types of modelling tools—commercial and open-source—utilized by scientists and engineers in the field. This research is among a few studies on 3D physical and numerical models for landslide-generated waves, and it is the first time that the aforementioned two models are systematically compared. We show that the two models accurately reproduce the physical experiments and give similar performances in modelling landslide-generated waves. However, they apply different approaches, mechanisms and calibrations to deliver the tasks. It is found that the results of the two models are deviated by approximately 10% from one another. This guide helps engineers and scientists implement, calibrate, and validate these models for landslide-generated waves. The validity of this research is confined to solid-block subaerial landslides and their impact in the near-field zone.

High-resolution wave modeling of the Southwestern Nigerian coastal shelf: Implications on geomorphic contrasts between barrier-lagoon and mud coasts

This study characterizes the spatio-temporal wave variability along Southwestern Nigerian coastal and shelf areas in the Gulf of Guinea. This is to provide further insight into the hydrodynamic factors that influence geomorphologic changes on the low-lying coast. Reanalysis wind-field datasets are employed to generate hourly wind forcing for an unstructured WAVEWATCH III model to simulate some bulk wave parameters. The model is validated against data from offshore buoys and satellite altimetry at selected locations near the coast. Results show that the waves have an annual average of significant wave height (Hs), peak period (Tp), and wind speed (u) of ∼0.5 m, 4.1 s, and 3.9 m/s, respectively. They exhibit seasonal spatial variability that is highest in the peak rainy season from July to September (Av. Hs: 0.56–0.79 m; Av. Tp: 4.68–5.18 s; Av. u: 4.30–5.22 m/s) and lowest in the early dry season from November to January (Av. Hs: 0.26–0.34 m; Av. Tp: 3.37–3.80 s; Av. u: 3.25–3.50 m/s). Also, the monthly averaged wave power varies from 0.2 to 2.8 kW/m annually. However, a maximum Hs of 2.2 m that generated power of 9.4 kW/m for 11.1 s was recorded during the peak of the rainy season in August. Overall, waves with relatively low intensity, which can be classified as smooth to moderate, propagate from the southwest direction and decrease towards the coast. The higher Hs and Tp recorded during the peak of rainy and end of dry seasons are attributed to the influence of far-away swells. A comparative assessment indicates that the Barrier-Lagoon coast is highly controlled by waves, while the Mahin mud coast, which witnesses frequent flooding events that degrade its shoreline, has little wave influence. Thus, local subsidence that increases the relative sea level is suggested to be taking place at sections of the muddy coast. This information is crucial for the sustainable engineering design and management of low-lying coasts.

WAVEWATCH III Hybrid Parallelization for Azov Sea Wave Modeling

WAVEWATCH III Hybrid Parallelization for Azov Sea Wave Modeling

Channel Modeling of Electromagnetic Wave in Sea Water Medium

Channel Modeling of Electromagnetic Wave in Sea Water Medium

3D numerical modeling of wave–monopile–seabed interaction in the presence of a scour hole

Coastal engineers are deeply concerned about wave-induced seabed instability around monopile foundations. Most prior studies have primarily focused on the seabed response around monopiles on flat seabeds, often neglecting the presence of scour holes commonly found in engineering practice. This study thoroughly investigates seabed response and liquefaction around monopiles of scour holes. The examination involves analyzing 3D flow velocities, dynamic wave loads, pore pressures, soil effective stresses, and wave forces around a monopile with a scoured profile. The analysis uses a model that integrates the interactions between waves, seabed, and structures, and it is implemented within the OpenFOAM framework. The study meticulously assesses the impact of scour holes on seabed responses and liquefaction zones around monopile foundations. Numerical results reveal that: (1) The magnitude of the pore pressure within the scoured seabed is reduced relative to a flat seabed; (2) Considering the scour hole effect leads to a more uniform distribution of liquefaction depth around the monopile; (3) This effect intensifies with a higher saturation degree, while it exhibits a pattern of increase, followed by a decrease with an increase in permeability.

Tsunami deposits in Tunisia contemporaneous of the large 365 CE Crete earthquake and Mediterranean Sea catastrophic event

New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery. The chaotic layer truncates sandy-silty paleosol, covers Roman settlements and is overlain by fire remains, a thin sandy-silty aeolian unit and ~ 1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets the catastrophic unit between 286 and 370 CE. Other historical investigations on the Roman sites of Neapolis (Nabeul), Hadrumete (Sousse), Thyna (Sfax), Meninx in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) evidenced major damage and abandonment of sites in the fourth century (16, 41, 42, 43, 44). The new identification of catastrophic deposits, offshore-onshore correlations with turbidites and modelling of tsunami waves suggest the relationship with the 21 July 365 tsunamigenic earthquake (Mw ~ 8) of west Crete (Greece) and call for a better estimate of tsunami risk on the Mediterranean coastlines.

Finite-difference frequency-domain method with QR-decomposition-based complex-valued adaptive coefficients for 3D diffusive viscous wave modelling

Abstract The diffusive viscous (DV) model is a useful tool for interpreting low-frequency seismic attenuation and the influence of fluid saturation on frequency-dependent reflections. Among present methods for the numerical solution of the corresponding DV wave equation, the finite-difference frequency-domain (FDFD) method with complex-valued adaptive coefficients (CVAC) has the advantage of efficiently suppressing both numerical dispersion and numerical attenuation. In this research, the FDFD method with CVAC is first generalized to a 3D DV equation. In addition, the current calculation of CVAC involves the numerical integration of propagation angles, conjugate gradient (CG) iterative optimization, and the sequential selection of initial values, which is difficult and inefficient for implementation. An improved method is developed for calculating CVAC, in which a complex-valued least-squares problem is constructed by substituting the 3D complex-valued plane-wave solutions into the FDFD scheme. The QR-decomposition method is used to efficiently solve the least-squares problem. Numerical dispersion and attenuation analyses reveal that the FDFD method with CVAC requires ∼2.5 spatial points in a wavelength within a dispersion deviation of 1% and an attenuation deviation of 10% for the 3D DV equation. An analytic solution for 3D DV wave equation in homogeneous media is proposed to verify the effectiveness of the proposed method. Numerical examples also demonstrate that the FDFD method with CVAC can obtain accurate wavefield modelling results for 3D DV models with a limited number of spatial points in a wavelength, and the FDFD method with QR-based CVAC requires less computational time than the FDFD method with CG-based CVAC.

Great Lakes wave forecast system on high-resolution unstructured meshes

Abstract. Wind-wave forecasts play a crucial role in the North American Great Lakes region towards ensuring the safety of communities, enhancement of the economy, and protection of property. Modeling wind waves in closed and relatively shallow basins with complex bathymetry like the Great Lakes is a challenge that is successfully tackled in part by using variable-resolution triangular unstructured meshes with no limits in terms of computational scalability and maximum resolution in the coastal areas. In this paper, we discuss recent advances in developing unstructured mesh capabilities as part of the spectral wave model WAVEWATCH III, in the context of National Oceanic and Atmospheric Administration (NOAA) operational requirements such as model robustness, efficiency, and accuracy. We revisit the history of developments leading to the transition from rectilinear to curvilinear grids and finally to an unstructured mesh version of NOAA's operational Great Lakes wave modeling system (GLWUv2.0). The article describes the development of the operational GLWUv2.0, from mesh design and scalability analysis to validation and verification for hindcast of storm cases and re-forecast using 4 months of retrospective simulations. In closed Great Lakes basins untouched by swell from distant sources, the atmospheric model's direct impact on wave behavior stands apart, showing reduced forecast accuracy over time, while maintaining consistent precision in accurately wind-hindcasted stormy conditions.

Modeling and numerical simulation of a type of pure-viscoacoustic-wave equation in attenuated transversely isotropic media

The anisotropy and attenuation features of subsurface media significantly affect seismic data processing. Ignoring anisotropy and attenuation in seismic wave propagation may result in inaccurate reflector positions, dimming amplitudes, and reduced spatial resolution in the imaging results. Therefore, accurate seismic wave modeling of anisotropy and attenuation is essential for understanding wave propagation in the earth’s interior. This paper derives three pure-viscoacoustic-wave equations from characterizing the earth’s frequency-independent Q behavior in transversely isotropic (TI) media. First, we develop three time-space domain pure-qP-wave equations in TI media based on different approximation methods, whose coefficients can be determined by different approximation methods and Thomsen’s anisotropic parameters [Formula: see text], [Formula: see text]. Subsequently, we introduce the Kelvin-Voigt attenuation model into our derived three time-space domain pure-qP-wave equations and then obtain three pure-viscoacoustic-wave equations. To further demonstrate the effectiveness and accuracy of our methods, we provide some 2D and 3D numerical tests. The numerical results indicate that the wavefield generated by pure-qP-wave equations and pure-viscoacoustic-wave equations have accurate kinematic characteristics of qP-wave in TI media and attenuated TI media and are free of S-wave artifacts while remaining stable under Thomsen’s anisotropic parameters [Formula: see text], so our methods have broader applicability compared with some existing methods. At the same time, the simulation results of pure-viscoacoustic-wave equations also reflect the absorption and attenuation characteristics of qP-waves in attenuated TI media.

Modeling of Flexural-Gravity Waves in Ice Cover on Elastic Films

Modeling of Flexural-Gravity Waves in Ice Cover on Elastic Films

Validation and Application of the Accu-Waves Operational Platform for Wave Forecasts at Ports

This paper presents a recently developed Operational Forecast Platform (OFP) for prevailing sea conditions at very important ports worldwide (Accu-Waves). The OFP produces reliable high-resolution predictions of wave characteristics in and around ocean ports. Its goal is to support safer navigation, predict possible port downtime, assist vessel approaching, enhance management of towing services, and bolster secure ship maneuvering in busy ports around the globe. Accu-Waves OFP is based on integrated, high-resolution wave modelling over the continental shelf and in coastal areas that incorporates data from global- and regional-scale, open-sea wave and ocean circulation forecasts as boundary conditions. The coupling, nesting, calibration, and implementation of the models are reported and discussed in this paper, concerning 50 selected areas near and inside significant port basins. The detailed setup of the Accu-Waves OFP and its sub-system services is also provided regarding three-day forecasts at three-hourly intervals. The validation of the wave forecast system against in situ observations from wave buoys in coastal areas of the USA, Belgium, and Spain, as well as other model predictions by established OFPs, seems very promising, with performance skill scores ranging from adequate to very good. An exceptional case of stormy seas under severe marine weather conditions with very high wave maxima (>10 m) in the port of Algeciras is further discussed, confirming the good performance of the Accu-Waves OFP.

Modeling of Linear Magnetosonic Waves of Two Ion Species In the Martian Magnetosphere

Modeling of Linear Magnetosonic Waves of Two Ion Species In the Martian Magnetosphere