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Based on the RANS equations and applying the waves2Foam solver in OpenFOAM, the study numerically investigated the turbulent kinetic energy (TKE) generated due to emergent rigid vegetation in water waves. The numerical results show that the TKE generated due to emergent vegetation in water waves increases with decreasing water depth and increasing wave height and period, as well as vegetation density and stem diameter. Moreover, compared to wave height, the influence of wave period on the stem-generated TKE in waves is more significant. Furthermore, the ratio of the amplitude of wave motion trajectory to stem spacing has a significant impact on the stem-generated TKE in waves. When the amplitude of wave motion trajectory is less than half of the stem spacing, the stem-generated TKE in waves is similar to the TKE of the bare bed in waves. In the case where the amplitude of wave motion trajectory is greater than half of the stem spacing, the stem-generated TKE in waves in the front of the vegetation will be significantly enhanced. Based on the study, an improved formula is proposed for predicting the stem-generated turbulence in waves. • Stem-generated turbulent kinetic energy in waves increases with decreasing water depth and increasing wave height and period. • Stem-generated turbulent kinetic energy in waves increases with increasing plant density and stem diameter. • Influence of the ratio of wave excursion to stem spacing on stem-generated TKE in waves. [ABSTRACT FROM AUTHOR]

In recent years, AI (artificial intelligence) algorithms based on big data have gradually emerged and been applied to short time predictions of ocean waves (e.g. 1 h, 3 h, ..., 48 h). However, limited by the lack of a better method and time-consuming computation, long time (e.g. 720 h) predictions have not been investigated yet. Based on the problems with study of long time series wave prediction, by using the hourly wave reanalysis data near Bering Sea from 2016 to 2020, this study establishes a long time series AI prediction model for waves with a forecast length of one month (720 h) based on PatchTST model. The time series prediction results of significant wave height evolution in 2021 show that compared with Informer, LSTM (Long Short Term Memory) and NeuralProphet, PatchTST's is significantly superior with COR (Correlation) averages at 0.90, RMSE (Root Mean Square Error) averages at 0.65 and MAE (Mean Absolute Error) averages at 0.56 on 12 months of 2021, which can be effectively applied to long time significant wave height prediction. • AI model based on the PatchTST algorithm for predicting the long-term evolution of ocean waves. • PatchTST algorithm is effective and accurate in predicting wave height evolution. • The gap between long-term wave forecasting and short-term wave forecasting. [ABSTRACT FROM AUTHOR]

The traditional error model for strapdown inertial navigation system (SINS)/Doppler velocity log (DVL) integrated navigation is establish for special orthogonal group Kalman filter (SOKF), which is only suitable for the case of small misalignment angle. In this article, the Lie group based nonlinear error model is investigated for SINS/DVL in inertial frame, this model is no longer limited by the size of misalignment angle like traditional SOKF, so initial alignment and integrated navigation could be combined into one stage, and the navigation solution is more accurate and faster. First, a thorough theoretical analysis is presented for state transformation extended Kalman filter (STEKF) modeling in both special orthogonal group (SO(3)) and special euclidean group (SE(3)). Then, the nonlinear error models (both left and right invariant error models) in inertial frame are derived in extended special euclidean group (SE 2 (3)). On this basis, SINS/DVL is verified as a type of left invariant observation system which is more applicable to the left invariant error model. Finally, both simulation and field test for SINS/DVL are conducted to evaluate the actual performance of the investigated methods. The results show that the proposed left invariant error model in inertial frame performs better for SINS/DVL than right invariant error model, and it also has more excellent performance than other existing integrated navigation methods, such as SOKF and STEKF. Especially compared with the current advanced invariant error model defined in earth frame, the model we investigated is more concise, efficient and accurate. • A thorough theoretical analysis is presented for STEKF modeling in both special orthogonal group (SO(3)) and special euclidean group (SE(3)). The inherent defects of STEKF are discussed from linearized modeling and Lie group theory. • A new navigation state is defined in inertial frame extended special euclidean group (SE 2 (3)), which is proved to satisfy the group affine property. The left and right invariant error models corresponding to the aforementioned state are derived for SINS/DVL integrated navigation. SINS/DVL is discussed as a type of left invariant observation system based on the analysis of transition matrices. • The simulation and field test are conducted to evaluate the actual performance of the investigated nonlinear error models. The results are explicitly presented with thorough discussion, which are consistent with theoretical analysis. The proposed left invariant error model in inertial frame outperform the common models (such as SOKF and STEKF) on the state estimation. Especially compared with the current advanced invariant error model defined in earth frame, the model we investigated is more concise, efficient, and accurate. [ABSTRACT FROM AUTHOR]

This study provides a numerical model to investigate the influences of breakwater layout on coastal waves, wave-induced currents, sediment transport and beach morphological evolution in the vicinity of breakwater. The numerical model is developed based on the sub-models for nearshore wave, wave-induced current, sediment transport and beach morphological evolution. Nearshore wave is simulated based on the parabolic mild-slope equation considering wave refraction, diffraction and breaking effects. Wave-induced nearshore current is modeled using the nonlinear shallow water equations in which wave radiation stresses are provided by wave model for driving current. Then, the two-dimensional suspended sediment transport equation, bed-load equation and coast beach morphological evolution are coupled with the wave and current models for simulating sediment transport and morphological evolution in coastal waves and wave-induced currents. The numerical model is firstly tested by the experiment results for coastal waves, near-shore currents, sediment transport and beach morphological evolution around breakwater from the Large-scale Sediment Transport Facility at the US Army Corps of Engineer Research and Development Center ( Gravens and Wang, 2007 ). Then the model is used to study the influences of breakwater layout on coastal waves, wave-induced currents, sediment transport and beach morphological evolution by set several breakwater layouts in the LSTF basin. [ABSTRACT FROM AUTHOR]

An adaptive fuzzy nonlinear integral sliding mode control strategy based on an extended state observer (ESO) is proposed for trajectory tracking of unmanned underwater vehicles (UUVs) in the presence of unknown external disturbances and model parameter uncertainties. A nonlinear dynamics error model of the UUV is established; the estimation of the lumped disturbances are estimated using ESO, and the control variables are compensated for in real time. A nonlinear integral sliding mode controller with saturation characteristics is designed to improve the transient and steady-state performance of the system, and the switching gain of the sliding mode control is adaptively adjusted using the fuzzy logic system, such that the weight of the output changes with the sliding mode surface; thus, the chattering of the control variables is weakened. The asymptotic stability of the control system is verified using Lyapunov stability theory. The simulation and experimental results demonstrated that the designed control strategy effectively suppresses the system lumped disturbances with high tracking accuracy and robustness. • The strategy is based on the combination of a nonlinear integral sliding mode control technique with an extended state observer. • The extended state observer achieves an effective estimation of the lumped disturbances. • The nonlinear integral sliding mode controller improves the transient and steady-state performance of the system. • The adaptive fuzzy switching rate reduces the chattering phenomenon. • Asymptotic stability of the control system is verified by Lyapunov stability theory. [ABSTRACT FROM AUTHOR]

The effects of rigid emergent vegetation on wave overtopping have been studied by numerical simulation in this study. The numerical model is based on second-order fully nonlinear Boussinesq equations and solved by a combination of finite difference and finite volume methods. Physical laboratory results of wave propagation in the vegetated area and wave overtopping on a bare slope were used to validate the capability of the model, and the numerical and experimental results agreed well, which indicated that the model can well predict wave overtopping on a vegetated slope. Then, based on the model, the effects of rigid emergent vegetation on wave overtopping were investigated. The results showed that the wave overtopping volume decreases exponentially with the increase of vegetation volume per unit water volume V veg / V w , and the wave overtopping volume can be decreased by 50% when V veg / V w equals 0.01. • Influences of rigid emergent vegetation on regular wave overtopping. • Effects of plant diameter, vegetation density and volume on wave overtopping. • Effects of wave period and height on wave overtopping. [ABSTRACT FROM AUTHOR]

The regular wave attenuation in following and opposing currents due to rigid, emergent vegetation has been studied by physical and numerical simulation in this study. Firstly, laboratory experiments were conducted to investigate the effect of currents on wave attenuation due to vegetation. Then, to overcome the limitation of the experimental conditions, a numerical model, based on the Boussinesq equations and validated by the experimental results, was applied to further investigate the effects of current velocity, vegetation density and water depth on wave attenuation due to vegetation in currents with larger α (the ratio of current velocity to the amplitude of the horizontal wave orbital velocity) range. The results show that both following and opposing currents can enhance or suppress wave attenuation due to vegetation depending on α. For the studied vegetation densities and water depths, the effect of wave attenuation due to vegetation in currents first decreases and then increases with the increase of α. Moreover, wave attenuation due to vegetation in currents is increased with the increase of vegetation density and decreased with the increase of water depth, and both of them have no influence on the relationship between relative wave height decay and α. • Wave attenuation in following and opposing currents due to rigid vegetation. • Influences of current direction and velocity on wave attenuation due to vegetation. • Influences of vegetation density and water depth on wave attenuation by vegetation in currents. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to investigate the effects of currents on solitary wave attenuation by rigid vegetation. In the experiments, the vegetation was simulated by cylinders, and the oscillation of cylinder was ignored. The experimental results showed that vegetation could effectively attenuate solitary wave. In positive currents, the wave attenuation rate in vegetation zone increases with increasing current velocity. However, in oppositive currents, the wave attenuation rate does not vary monotonously with increasing current velocity. The ratio of current velocity to the horizontal velocity of solitary wave has influence on wave attenuation effects in vegetation zones. For a small velocity ratio, positive currents would enhance wave attenuation due to vegetation, while oppositive currents weaken it. For a larger velocity ratio, wave attenuation due to vegetation is increased in both positive and oppositive currents. The solitary wave attenuation rate due to vegetation increases with increasing velocity ratio when velocity ratio is larger than the value at the transition point in both positive and oppositive currents. Moreover, positive currents increase the attenuation of solitary wave velocity in vegetation zone up to 46% while oppositive currents decrease it up to 23% compared to those in the absence of currents in the experiments. • Experimental study on vegetation attenuation effects on solitary wave in currents. • Effects of positive current on solitary wave height and velocity in vegetation. • Effects of oppositive current on solitary wave height and velocity in vegetation. [ABSTRACT FROM AUTHOR]

Coastal vegetation is capable of reducing wave run-up and protecting coasts from flooding and land loss. This study numerically investigates the effect of width of emergent rigid vegetation on wave run-up attenuation. The numerical model is based on two-order fully nonlinear Boussinesq equations and solved using a combination of finite difference and finite volume methods. Physical laboratory data pertaining to long period wave run-up on a bare and emergent vegetated sloping beach is used to validate the accuracy of the model. Next, based on the model, the effect of vegetation zone width on wave run-up attenuation is investigated. The numerical results indicate that coastal vegetation can considerably decrease the wave height and wave run-up, and the wave run-up decreases monotonously with increase in the vegetation width. Moreover, the reduction rates of the wave height and wave run-up, caused by the vegetation zone, demonstrate an overall increasing trend with increase in the wave period when the ratio of vegetation zone width and wave length is constant. • Numerical simulation for coastal wave run-up on vegetated sloping beach. • Attenuation effects of vegetation on coastal wave run-up. • The effect of width of vegetation on wave run-up attenuation. [ABSTRACT FROM AUTHOR]

Globally, many estuarine areas are suffering from large-scale land reclamations to fulfill the land demands of city expansion. Understanding the wave and storm surge evolutions in response to human reclamations in estuaries is of vital importance regarding estuarine management (e.g., reclamation plan formulation, flood mitigation). The wave and storm characteristics, and their responses to 1990–2020 land reclamations in the Pearl River Estuary (PRE) were investigated by a storm surge model. Besides, the impacts of increasing typhoon intensity (TI) on the changes of waves and storm surges caused by reclamations were also illustrated under the background of global warming. Simulated results show that reclamations cause apparent variations of wave height and storm surge fields in the PRE. The wave height and surge height also increase with the enhancement of TI, consequently influencing the wave height and surge height change rates caused by reclamations. Furthermore, the combined actions of land reclamation and increased TI conduct the most remarkable effects and bring the highest surge height compared with other scenarios. Particularly, the maximum wave height and surge height can reach 0.88–2.31 m and 2.71–3.77 m along the seawalls of Zhuhai, respectively, indicating more enormous seawall submersion and inland flooding. [Display omitted] • Land reclamations cause apparent variation of wave and storm surge fields. • Wave height and surge height present higher values for larger typhoon intensity, thus changing reclamation impacts. • The combination of land reclamation and increased typhoon intensity causes more enormous inland flooding. [ABSTRACT FROM AUTHOR]

The hydrodynamics and water quality evolutions in response to the land reclamations in Bohai Bay were investigated by developing a coupled hydrodynamics-water quality model. Simulated results indicate reclamations considerably change the residual current fields and decrease the tidal prisms. After 1990–2006 reclamations, salinity isolines in the west of the bay obviously move towards open sea, and cause the decrease of salinity value. Compared with the 2006 reclamation scenario, the 2022 reclamation scenario generates larger salinity concentration, thereby intensifying salinity intrusion. Besides, a large amount of dissolved inorganic nitrogen (DIN) is retained in the bay and increases its concentration value due to 1990–2006 reclamations, which almost presents opposite variation in the 2022 reclamation scenario. 1990–2006 reclamations increase phytoplankton carbon concentrations in the most bay areas, with a maximum increased value of 53.37 μg/L. With the further construction of reclamations (2006–2022), phytoplankton carbon concentrations increase within several estuarine areas, nevertheless the decreases appear in the large areas from estuarine mouths to bay's center. Statistically, the averaged salinity concentration slightly changes in the whole bay, while the averaged DIN and phytoplankton carbon concentrations significantly increase by 14.92% and 13.33% during 1990–2006, then they decrease by 16.02% and 20.68% during 2006–2022, respectively. [Display omitted] • A coupled hydrodynamics-water quality model is established in Bobai Bay. • Land reclamations change residual current fields and decreases tidal prisms. • Land reclamations affect spatial distributions of water quality parameters. • Averaged dissolved inorganic nitrogen and phytoplankton carbon increase by 14.92% and 13.33% after 1990–2006 reclamations. • Nevertheless they decrease by 16.02% and 20.68% due to 2006–2022 reclamations. [ABSTRACT FROM AUTHOR]

The mechanism that underlies the evolution of the seasonal environment and the effects of reclamation projects in the Pearl River Estuary (PRE) were studied by modeling the hydrodynamics, suspended sediment, and water quality. Due to the seasonal variation of the freshwater discharge, the residual currents in the estuary are generally larger during the summer than during the winter. Reclamation projects significantly affect the residual current fields and decrease tidal prisms across the PRE, resulting in the variation of water exchange and material transport process. During the summer, waters high in chlorophyll -a move downstream, with increased seaward residual currents, and they more widely range from the middle estuary to the estuarine mouth than during the winter; moreover, the chlorophyll -a value peaks in these areas. Reclamation projects significantly promote the expansion of waters high in chlorophyll -a towards the estuarine mouth. The distribution of suspended sediment, nitrate, ammonium, and silicate also obviously varies with altered water exchange and chlorophyll -a distribution. Average chlorophyll -a , suspended sediment, and silicate concentrations in the whole computational domain increase by 12.71%, 15.19%, and 1.91%, respectively, while the growth of algae consumes a large amount of nitrate and ammonium. • Reclamations in the Pearl River Estuary significantly affect the water quality. • Chlorophyll -a , suspended sediment, and silicate concentrations increase after reclamations. • Nitrate and ammonium concentrations decrease by 28.82% and 19.09%, respectively. [ABSTRACT FROM AUTHOR]

The time required for water renewal in an estuary is closely related to its self-purification ability and environment degree. A FVCOM-based water age (WA) model was conducted to investigate the renewal timescale in the Pearl River Estuary (PRE) under various hydrodynamic scenarios. Model sensitivities revealed the depth-averaged WA during the summer was significantly smaller than that during the winter; meanwhile, the region with vertically significant variations in the WA varied from almost the whole estuary to the downstream. It can be explained that the seaward residual currents became stronger and narrowed the region of vertical circulations by impeding salinity invasion and stratification. During typhoon Hagupit, the depth-averaged WA was apparently increased in the most of the estuary because the horizontal water circulations between the estuary and open sea were significantly decreased by the strong up-estuary surge-waves. Moreover, the vertical WA distribution almost became a single-layer structure with the severely weakened vertical circulations. After reclamations, the variable shorelines in the PRE significantly affected the hydrodynamic characteristics and water circulations, thus the depth-averaged WA complicatedly changed, and the vertical difference of the WA values slightly increased in narrowed waterways and their downstream due to the limited effects on the vertical circulations. • A 3D water age (WA) model is built to quantify water renewal in the Pearl River Estuary (PRE). • The WA in the PRE was characterized by significantly spatial distributions and seasonal variations. • The WA was significantly increased in the most areas and less stratified in vertical direction during typhoon Hagupit. • After reclamations, the WA complicatedly changed in horizontal direction and became more stratified in vertical direction. [ABSTRACT FROM AUTHOR]

Abstract: This study extends previous two-dimensional research [Wang, S.D., Shen, Y.M., Zheng, Y.H., 2005. Two-dimensional numerical simulation for transport and fate of oil spills in seas. Ocean Engineering 32, 1556–1571] to three dimensions in order to investigate the vertical dispersion/motion of the spilled oil slick, which is a more realistic model of the motion of the spilled oil. To this end, a three-dimensional (3-D) model, based on the particle approach, is developed for simulating oil spill transport and fate in seas. The amount of oil released at sea is distributed among a large number of particles tracked individually. These particles are driven by a combination of water current, wave- and wind-induced speed and move in a 3-D space. Horizontal and vertical diffusion are taken into account using a random walk technique. The model simulates the most significant processes which affect the motion of oil particles, such as advection, surface spreading, evaporation, dissolution, emulsification, turbulent diffusion, the interaction of the oil particles with the shoreline, sedimentation and the temporal variations of oil viscosity, density and surface tension. In addition, the processes of hydrolysis, photo-oxidation and biodegradation are also considered in this model. The model has been applied to simulate the oil spill accident in the Bohai Sea. [Copyright &y& Elsevier]