Hydrodynamic Numerical Model Research Articles

Optimal experimental design for identification of hydrodynamic loading models

Abstract Hydrodynamic model-scale experiments are an intrinsic part of the design of marine structures, as they enable validating and calibrating the involved hydrodynamic numerical models. Such seakeeping experiments are generally conducted using a simple spring-based mooring system, with fixed properties throughout the tests. In the context of cyber-physical testing, the marine structure is kept in position in the laboratory by a virtual mooring system, the properties of which can be adjusted on the fly. This paper provides an algorithmic approach for maximizing the information gain from the test by optimizing the mooring stifness and damping parameters that define the experiment. The method is verified with synthetic data generated for the INO Windmoor 12MW floater, and is shown to be robust to noise and unmodeled effects.

Morphodynamic Cartography Visualization of Wulan River Estuary Systems from Space to Numerical Approach Based on Multi-Season Analysis

This research aims to investigate the morphodynamics of the Wulan River estuary in Demak Regency using the integration of multispectral remote sensing images and numerical modeling. In this study, PlanetScope for a manualvisual analysis of estuary morphodynamics and Sentinel-2 MSI Level 2A to obtain periodic total suspended solids (TSS) information for the east and west monsoon seasons. MIKE by DHI software used to develop hydrodynamic numerical modeling in order to characterize the current circulation and sediment transport model. Based on a marine cartography aspect, the obtained results illustrated that the climatological phenomenon of seasonal forcing plays a role in the development of the current circulation and indirectly influences the sediment transport. During the west season, the morphodynamics in the Wulan River estuary are much more massive and significant as compared to the east season. A projection of the deposition that results from the sediment transport is described in the bed-thickness change; this occurs in the western part of the Wulan River estuary during the east season, while the bed-thickness change occurs predominantly in the northern part during the west season (where there was previously a beach sandbar phenomenon). This was verified through multi-temporal satellite imagery that the deposition that occurs in the northern part of the Wulan River estuary during the west season is increasingly progressive and massive.

Application of tracer studies results for adaptation of hydrodynamic models of oil fields

To date, a large array of tracer results has been accumulated, which are mainly processed analytically without further use in numerical hydrodynamic modelling, despite the fact that most commercial hydrodynamic simulators have modules for tracer modelling, which is undoubtedly an omission. Using the results of tracer studies makes it possible to select a filtration model, to specify both filtration-capacitance properties of productive sediments of the interwell space and the type of void space, which can serve as valuable factual material for analyses and development design.

A Numerical Hydrodynamic Model of a Long Segment of the Ural River and Its Application to Assessing the Inundation Risk of Residential Areas by Floods and Breakthrough Waves

A Numerical Hydrodynamic Model of a Long Segment of the Ural River and Its Application to Assessing the Inundation Risk of Residential Areas by Floods and Breakthrough Waves

Storm surge modelling along European coastlines: The effect of the spatio-temporal resolution of the atmospheric forcing

The spatio-temporal resolution of atmospheric forcing plays a key role in the accuracy of simulated storm surges with hydrodynamic numerical models. Here, we generate five hydrodynamic hindcasts of coastal storm surges along the European Atlantic and the Mediterranean Sea coasts, forced with atmospheric fields of varying temporal (hourly and daily) and spatial (0.25° to 2°) resolution since 1940. Our results, that are validated with insitu tide gauge observations, show that storm surges obtained with daily forcing underestimate the magnitude of coastal extreme sea level events by up to 50% compared to hourly simulations and observations. Nevertheless, low-resolution simulations capture the temporal variability of storm surges, including strong episodes. Furthermore, taking advantage of the consistent set of coastal storm surge hindcasts, we demonstrate that storm surges forced with daily mean atmospheric fields, when bias corrected via quantile mapping, provide accurate values of daily maxima as calculated by a high-resolution hindcast. This transformation paves the way to obtain daily maxima storm surge estimates from low-resolution atmospheric fields, as those typically provided by large-scale and global climate models, at a lower computational cost.

On the use of hydrodynamic modelling and random forest classifiers for the prediction of hypoxia in coastal lagoons

Hypoxia is one of the fundamental threats to water quality globally, particularly for partially enclosed basins with limited water renewal, such as coastal lagoons. This work proposes the combined use of a machine learning technique, field observations, and data derived from a hydrodynamic and heat exchange numerical model to predict, and forecast up to 10 days in advance, the occurrence of hypoxia in a eutrophic coastal lagoon. The random forest machine learning algorithm is used, training and validating a set of models to classify dissolved oxygen levels in the lagoon. The Orbetello lagoon, in the central Mediterranean Sea (Italy), has provided a test case for assessing the reliability of the proposed methodology. Results proved that the methodology is effective in providing a reliable short-term evaluation of DO levels, with a high resolution in both time and space throughout an entire lagoon. An overall classification accuracy of up to 91 % was found in the models, with a score for identifying the occurrence of severe hypoxia - i.e. hourly DO levels lower than 2 mg/l - of 86 %. The use of predictors extracted from a numerical hydrodynamic model allows us to overcome the intrinsic limitation of machine learning modelling approaches which rely on input data from relatively few, local field measurements, i.e. the inability to capture the spatial heterogeneity of DO distributions, unless several measuring points are available. The methodological approach is proposed for application to similar eutrophic environments.

Development of a novel storm surge inundation model framework for efficient prediction

Abstract. Storm surge is a natural process that causes flood disasters in coastal zones and results in massive casualties and property losses. Therefore, storm surge inundation is of major concern in formulating appropriate strategies for disaster prevention and mitigation. However, traditional storm surge hydrodynamic models have large limits with respect to computational efficiency and stability in practical applications. In this study, a novel storm surge inundation model was developed based on a wetting and drying algorithm established from a simplified shallow-water momentum equation. The wetting and drying algorithm was applied to a rectangular grid that iterates through a cellular automata algorithm to improve computational efficiency. The model, referred to as the Hydrodynamical Cellular Automata Flood Model (HCA-FM), was evaluated by comparing the simulations to regional field observations and to a widely used hydrodynamic numerical model. The comparisons demonstrated that HCA-FM can reproduce the observed inundation distributions and predict results that are consistent with the numerical simulation in terms of the inundation extent and submerged depth with much improved computational efficiency (predicting inundation within a few minutes) and high stability. The results reflect significant advancement of HCA-FM toward efficient predictions of storm surge inundation and applications at large spatial scales.

A Runoff‐On‐Grid Approach to Embed Hydrological Processes in Shallow Water Models

AbstractCatchment‐scale hydrological models encountered dichotomies with the numerical hydrodynamic models when describing surface routing process. We propose a new modeling framework, the so‐called “Runoff‐On‐Grid” approach, for embedding distributed process‐based hydrological modeling into shallow water models, as an alternative to the traditional Fully Hydrodynamic Approach (also known as Rain‐On‐Grid). Antecedent Soil Moisture, subsurface dynamics, and other topsoil hydrological processes are implicitly integrated in the governing hydrodynamic equations via the proposed methodology. The resulting hydrological‐hydrodynamic coupling, based on the DREAM distributed hydrological model and the Iber+ shallow water model, enhances the capabilities of both reference models. Through introducing non‐negligible runoff generation sources, the Runoff‐On‐Grid approach extends the surface hydrodynamic modeling to medium‐sized vegetated and/or (semi)humid catchments, bypassing the limitations of the widespread hydrological losses' empirical formulations. Employed in an event‐based analysis within a High‐Performance Computing framework, the DREAM‐Iber model provides an efficient and reliable reconstruction of the November 2020 flood that occurred in Crotone (Italy), envisaging consequences of similar future scenarios. We show that the proposed modeling technique, nested within emerging environmental technologies and robust on‐site data, details the flood hazard inducing processes merging physical hydrology with advanced hydrodynamics.

Development of an Underwater Detection Robot for the Structures with Pile Foundation

Addressing the challenges for detecting underwater damage to the structures with pile foundation, this study presents the design of an adsorption-operated robotic system. Initially, a prototype is proposed for an adsorption-operated robot that is equipped with an automatic movement mechanism. To account for the disturbance of the drag force in the control system, a hydrodynamic numerical model for the detection robot is established. The numerical results of the drag force are then integrated into the control system, leading to the design of a force-redeemed active disturbance rejection controller. Furthermore, a novel detection algorithm based on the image segmentation network UNet is developed for the automatic identification of damages. The performance of the controller and detection algorithm is evaluated against traditional methods. The results indicate that the proposed force-redeemed active disturbance rejection controller outperforms traditional PID and ADR controllers in terms of overshoot and adjustment time. Moreover, the developed detection algorithm exhibits superior performance in precision, F1 score, and mean intersection over union compared to the traditional algorithms of FCN, PSPnet, Deeplabv3, and UNet. Overall, this paper advances the technology of autonomous robots for underwater detection in the structures with pile foundation.

Investigating landslide-induced tsunamis using a low-dissipation Riemann weakly compressible smoothed particle hydrodynamics model

In order to address the complex moving boundary problem and violent free-surface flows involved in the process of landslide tsunamis, this paper proposes a new low-dissipation Riemann-solver-based smoothed particle hydrodynamics (SPH) numerical model. In this model, the complex fluid-rigid slide interaction and friction effects on landslides are handled by an improved motion boundary approach based on a one-sided Riemann scheme. A weighted essentially non-oscillatory (WENO) reconstruction method is introduced to reduce excessive dissipation of the fluid caused by rigid landslide impact. The kernel gradient accuracy is assured by applying the corrected smoothed particle method (CSPM) into a continuity equation. Single-block and multi-block landslide tsunamis in two-dimensional (2D) or three-dimensional (3D) applications are simulated with different particle resolutions, and the results are compared to those of other numerical models and experimental results. The landslide trajectories obtained from the modified boundary model are in good agreements with the experimental values. Free-surface flows variations during the propagation are properly captured in the current simulations without introducing any artificial viscosity term, and the wave peaks exhibit deviations of −14%–10.5% from the experimental values, thus verifying the usability and robustness of the proposed Riemann-SPH model.

Biogeochemical dynamics underlying equilibrium between nitrogen fixation and denitrification and its impact on a coastal marine ecosystem model

Many ecosystem models have chronic issues that result in unrealistic oligotrophic conditions in the shallow coastal regions. This problem is attributed to the poorly resolved bottom boundary condition for ecological tracers; detritus reaching the bottom boundary in shallow water escapes the model domain resulting in continuously decreasing total nitrogen levels. The scaling for the problem is determined by a vertical length scale wd/δ, where wd is detritus sinking speed and δ is remineralization rate. For shallow water depths h≪wd/δ corresponding to shallow marginal coastal ocean regions where loss of nitrogen is significant, ecosystem models predict unrealistic oligotrophic water masses. To alleviate the problem, the classical Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model is expanded here to consider denitrification and nitrogen fixation. Internal dynamics of the expanded model are examined through steady-state solutions. The intensity of denitrification, scaled as the ratio between wd/δ and water depth, plays an important role sustaining nitrogen fixers by regulating phosphorus competition with normal phytoplankton. The theoretical equilibriums of the expanded model well represent characteristics of coastal and pelagic ecosystems. The expanded ecosystem model is then fully coupled with a numerical hydrodynamics model and compared with the classical NPZD model. It is shown that unrealistic oligotrophic conditions along the coast predicted by the classical NPZD model are not present when denitrification and nitrogen fixation processes are considered because strong denitrification (loss of nitrogen) in the shallow region enhances nitrogen fixation that compensates the loss.

Influence of bottom protection structures group on the hydraulic characteristics in sharp bends

Bottom protection (BP) is a commonly used engineering measure in river training. A 3D hydrodynamic numerical model is established to study the influence of the overall arrangements of BP structures on the hydraulic characteristics of the sharp bends. Under the action of the BP structures group, the maximum longitudinal flow velocity is closer to the water surface vertically and closer to the concave bank laterally compared with no BP. The high shear stress zones on the riverbed at the exit straight section of the bend do not occur. The so-called primary circulation after the apex of the bend gradually weakens and disappears. If the coverage rate of BP is increased to 1.5 times that of the sequential BP, the average longitudinal flow velocity near the bottom of BP decreases by 10% and the average bed shear stress at the outlet section of the bend decreases by 35%. In the staggered BP condition, the average bed shear stress at the outlet section of the bend is reduced by 23% compared with the sequential BP. Moreover, the results show that the protection effects of the dense BP and the staggered BP are better than that of sequential BP.

Evaluation of Different Numerical Approaches to Modeling Flood Flows Over Groynes

AbstractThe hydraulic resistance of groynes is an important factor in the determination of design flood water levels on rivers and the assessment of how much these levels are lowered by modifying the groynes. In standard one‐ or two‐dimensional numerical hydrodynamic models for flood risk management, groynes are commonly represented as subgrid features with a local energy loss according to a weir formula. We tested this representation by using a two‐dimensional horizontal mesh at various groyne submergence degrees by comparing the results with those of flume experiments. We also compared the results with simulations using different 2D and 3D approaches on finer grids that incorporate groynes in the bed topography. In one of the two tested 3D models, complete Reynolds‐averaged Navier‐Stokes equations were solved. The second tested 3D model was constructed simpler by assuming hydrostatic pressure distribution in the vertical direction. We employed Delft3D software in construction and execution of all models. One of the 3D models did predict the hydraulic resistance at low submergence better than the standard model, but it slightly underestimated the resistance at higher submergences. Despite differences in flow characteristics, weirs and groynes were found to produce similar flow resistances for the same height and boundary conditions. Simulations of groyne modifications showed that hydraulic resistance decreased nonlinearly with groyne lowering and streamlining.

Simulating sea level extremes from synthetic low-pressure systems

Abstract. In this article we present a method for numerical simulations of extreme sea levels using synthetic low-pressure systems as atmospheric forcing. Our simulations can be considered to be estimates of the high sea levels that may be reached when a low-pressure system of high intensity and optimal track passes the studied region. We test the method using sites located along the Baltic Sea coast and simulate synthetic cyclones with various tracks. To model the effects of the cyclone properties on sea level, we simulate internal Baltic Sea water level variations with a numerical two-dimensional hydrodynamic model, forced by an ensemble of time-dependent wind and air-pressure fields from synthetic cyclones. The storm surges caused by the synthetic cyclones come on top of the mean water level of the Baltic Sea, for which we used a fixed upper estimate of 100 cm. We find high extremes in the northern Bothnian Bay and in the eastern Gulf of Finland, where the sea level extreme due to the synthetic cyclone reaches up to 3.5 m. In the event that the mean water level of the Baltic Sea has a maximal value (1 m) during the cyclone, the highest sea levels of 4.5 m could thus be reached. We find our method to be suitable for use in further studies of sea level extremes.

Numerical modeling of hydrodynamics of spouted bed in solid fuel boiler

The issues of numerical modeling of hydrodynamics of a spouted fuel bed in the furnace of a solid-fuel boiler are considered. At present, solid-fuel boilers are widely used in the power industry of the Russian Federation, with the share of coal-fired generation to remain significant in the projected terms. Therefore, the study of the efficiency of thermal and hydrodynamic processes that ensure the implementation of clean coal technologies is a relevant task both today and in the long term. The article presents the following main stages of numerical modelling of the hydrodynamics of the spouted bed: problem formulation with selection of boundary and initial conditions, methods of solving the Navier-Stokes and continuity equations for the air flow, Newton's equations and diffusion equations for particles. The k-omega turbulence model was used in the calculations that is described by means of two partial differential equations for the variables k (kinetic energy of turbulence) and omega (specific dissipation rate). A comparative analysis of environmental advantages and disadvantages of existing methods of combustion of low-grade coal in schemes with in-cycle gasification (ICG) is carried out. Advantages and difficulties of switching to structures with CFB in the spouted bed mode are shown. Numerical modeling of the cold spouted bed created by means of particle injection is performed, a set of initial settings and boundary conditions is presented, the adequacy of the obtained results is verified by hydrodynamic characteristics of the isothermal process. The obtained results allow us to proceed to the next stages with non-isothermal models, with heat exchange and combustion reactions in the spouted bed of coal taken into account. The following refinement of the physical model will allow to achieve more accurate and reliable results and to ensure their correct scaling.

Numerical simulation and experimental validation on the mechanism of crater evolution in electrical discharge micromachining

The plasma-material interaction and evolution mechanism of a solitary crater governs the nature of the surface, either plain or textured, created through the electrical discharge micromachining (EDMM) process. Therefore, it is indispensable to understand the fundamentals of a single crater evolution, which involves melt pool hydrodynamics and material vaporization under intense plasma pressure. The plasma pressure during the workpiece heating phase alters the vaporization phenomenon and melt ejection, warranting an in-depth understanding. In light of this, the current work proposes a two-dimensional (2-D) multiphysics numerical model of the melt pool hydrodynamics during EDMM. The model incorporates thermal evolution along with the effects of active plasma pressure during the heating phase of the substrate with the help of a coupled thermo-fluidic model. The simulation results reveal the predominant role of plasma pressure on the crater morphology evolution, plasma flushing efficiency (PFE) and recast layer thickness (RLT). The predicted single crater profile is validated using single-spark experiments with reasonable agreement. Thereafter, the formation mechanism of a single crater has been extended to multi-crater creation for textured surface generation.

NUMERICAL SIMULATION OF ENERGY-EFFICIENT SOLUTIONS OF THE ARC FURNACE STEEL MELTING BATH

Numerical modeling of hydrodynamics and heat and mass transfer in the arc furnace (EAF) steel melting bath under pneumatic stirring conditions demonstrates that the introduction of a «deep» bath with a form factor (ratio of diameter to depth) of 2.5 against the traditional 5.0 provides an energy-efficient bubbling mode of purging at higher inert gas flowrate. An increase in the diameter of the porous plug and the volume of the two-phase region in the "deep" bath allows in 150-ton EAF to increase the mixing power and the coefficient of convective heat transfer in liquid steel by 2-2.2 and 1.4 times on average, respectively. In the context of the «flat bath» process, it is shown the possibility of intensifying the convective melting of scrap in the bath by 24% in average and, thus, increasing productivity and, accordingly, improving the energy efficiency of the EAF.

Enhancing Marina Sustainability: Water Quality and Flushing Efficiency in Marinas

Coastal marinas are particularly susceptible to pollution due to their limited flushing capabilities and ineffective management practices. Therefore, it is necessary to implement measures that promote enhanced sustainability. This study aims to explore the intricate relationship between tidal flushing characteristics and water quality within marinas to foster sustainable development and management practices that mitigate environmental impacts. The research scrutinized seven marinas along the Kuwait coastline, each exhibiting unique hydrodynamic conditions and geometric configurations. Water quality indicators such as BOD, COD, DO, and SO42− were evaluated concerning each marina’s flushing efficiency through field assessments and hydrodynamic numerical modeling. An empirical formula was developed to predict and optimize flushing mechanisms, which provided critical insights into the design and management of marinas to enhance water quality. The study revealed significant disparities in water quality across the examined marinas as the hydrodynamic and geometric conditions differed. The empirical formula developed offers a novel approach to quantitatively assessing flushing efficiency, which is valuable for marina designers and managers, facilitating informed decisions, and promoting environmental sustainability. This study underscores the critical importance of integrating hydrodynamic and geometric considerations in the design and management of marinas to improve water quality and sustainability. It advocates for a multifaceted strategy that includes advanced design solutions, rigorous policy implementation, and active community engagement to safeguard coastal marine environments. The findings emphasize the need for comprehensive environmental management plans.

Integrated Modeling of Coastal Processes Driven by an Advanced Mild Slope Wave Model

Numerical modeling of wave transformation, hydrodynamics, and morphodynamics in coastal regions holds paramount significance for combating coastal erosion by evaluating and optimizing various coastal protection structures. This study aims to present an integration of numerical models to accurately simulate the coastal processes with the presence of coastal and harbor structures. Specifically, integrated modeling employs an advanced mild slope model as the main driver, which is capable of describing all the wave transformation phenomena, including wave reflection. This model provides radiation stresses as inputs to a hydrodynamic model based on Reynolds-averaged Navier–Stokes equations to simulate nearshore currents. Ultimately, these models feed an additional model that can simulate longshore sediment transport and bed level changes. The models are validated against experimental measurements, including energy dissipation due to bottom friction and wave breaking; combined refraction, diffraction, and breaking over a submerged shoal; wave transformation and wave-generated currents over submerged breakwaters; and wave, currents, and sediment transport fields over a varying bathymetry. The models exhibit satisfactory performance in simulating all considered cases, establishing them as efficient and reliable integrated tools for engineering applications in real coastal areas. Moreover, leveraging the validated models, a numerical investigation is undertaken to assess the effects of wave reflection on a seawall on coastal processes for two ideal beach configurations—one with a steeper slope of 1:10 and another with a milder slope of 1:50. The numerical investigation reveals that the presence of reflected waves, particularly in milder bed slopes, significantly influences sediment transport, emphasizing the importance of employing a wave model that takes into account wave reflection as the primary driver for integrated modeling of coastal processes.

Numerical Hydrodynamic Modelling As A Tool For Research And Use Of Tidal Rivers

Tidal estuaries play a crucial role, serving as major hubs for economic activities while also contributing to the preservation of natural diversity and bioproductivity. In Russia, these estuaries are primarily located in remote regions of the European North and the Far East, making them vital for energy and transportation usage as they essentially form the ‘cores’ of territorial development along the Northern Sea Route. To facilitate the development of energy and navigation infrastructure in tidal estuaries, as well as to plan and implement environmental protection measures, it is essential to have a comprehensive understanding of their hydrological regime. Unlike regular river flow, tidal estuaries exhibit more complex hydrodynamics, influenced by both river and marine factors. Due to the considerable challenges of conducting field hydrological studies in remote areas, numerical hydrodynamic modelling has emerged as a valuable method for obtaining information on the flow and water level regime in tidal estuaries. This paper presents an application of one-dimensional HEC-RAS and two-dimensional STREAM_2D CUDA numerical models to investigate the parameters of reverse currents in the hypertidal Syomzha estuary flowing into the Mezen Bay of the White Sea. The limitations and accuracy of the models are discussed, along with the potential for their improvement considering recent advancements in understanding the hydraulics of reverse currents.