Hydrodynamic Model Research Articles

Brief communication: From modelling to reality – flood modelling gaps highlighted by a recent severe storm surge event along the German Baltic Sea coast

Abstract. In October 2023, the Baltic Sea coasts of Germany and Denmark experienced a severe storm surge, predominantly impacting the German state of Schleswig-Holstein and parts of southern Denmark. The surge led to extensive flooding in cities like Flensburg and Schleswig, causing the breaching of at least six (regional) dikes and causing over EUR 200 million in damages in Schleswig-Holstein. By chance, the peak water levels of this storm surge aligned well with those of recent hydrodynamic flood modelling studies of the region. This rare coincidence offers crucial insights for our understanding of flooding impacts, flood management, and modelling. By comparing those studies to the real-world example using extensive media reports, we aim to extract key insights and identify gaps to be tackled in order to improve flood risk modelling in the Baltic Sea region and beyond.

NEW ASPECTS OF CORE MICROTOMOGRAPHY

Compared to many other technologies of laboratory studies of core samples, the modern «digital core» technology is a rather young scientific and industrial direction, but for decades it has attracted close attention of a wide range of scientists and specialists of the oil and gas industry (geologists, sedimentologists, lithologists, geophysicists, developers, geological modelers, hydrodynamicists, physicists). For many specialists of practical sphere new methodical techniques and methods of such researches remain little known. If earlier computer X-ray microtomographs in the Russian Federation were the prerogative of only academic structures or service organizations, nowadays many subsoil users have started to equip their own laboratory and research centers with the corresponding specialized equipment, understanding that without these data it is hardly possible to build high-quality geological, petrophysical, tectonic-physical, rheological, hydrodynamic and geological-field models of the studied sediments, as well as to prepare progragmatic models of the studied sediments. In this article the authors made an attempt to study and analyze the current state of development of «digital core» technology.Using extensive factual material the accumulated experience of special studies in the field of full-size core tomography is summarized, estimates of absolute permeability of low-permeability complex sediments are made, results of studying cores in frozen and unfrozen state are given, detailed analysis of fracturing at different stages of sample preparation and ongoing studies is carried out, and specific problems for which a solution using the technology is expected in the near future are formulated In this article the positive and negative sides of poroset and direct methods of modeling of filtration properties by digital core model are studied. Particular attention is paid to the need for large-scale studies to obtain statistically reliable data samples, which can be used to select the most qualitative methods of research and application of algorithms for processing of initial geological and geophysical information.

IMPROVING THE RELIABILITY OF THE THREE-DIMENSIONAL GEOLOGICAL BASIS OF COMPLEX DEVELOPMENT TARGETS

This article proposes a new method for identifying different groups of reservoirs when constructing a three-dimensional geological and hydrodynamic model of the target. Productive formations of the Bajocian and Bathonian stages of the Jurassic system of the Kalamkas field were selected as the object of study. This field is tectonically associated with the northern part of the North Buzachinsky arch, located at the northwestern end of the Turan plate. It was noted that these productive deposits have a complex geological structure, due in lithological terms to uneven alternation of sand-siltstone and clay rocks. In addition, four different reservoir classes are identified within each tier, which are characterized by their own permeability-porosity correlation relationships. As a result, for reliable construction of the filtration field, it is necessary to determine the distribution zones of each of the identified reservoir classes within the reservoir. This is due to the fact that due to the different filtration field, the development of reserves from each group of reservoirs will occur unevenly both in area and in section. In this regard, the integrated Flow Zone Indicator (FZI) was evaluated using the results of laboratory core studies. In order to obtain a continuous FZI parameter for wells without core sampling and laboratory analysis, the results of laboratory studies were compared with the results of well geophysical studies (well logging). As a result, analytical dependence of FZI and log data was obtained. Based on this analytical dependence, new three-dimensional models were constructed and zones of distribution of different groups of reservoirs were identified. To verify the obtained results, the synthetic FZI curve calculated from the obtained analytical relationship was compared with the FZI estimate based on the results of laboratory core studies. It is concluded that the synthetic FZI curve is consistent with the FZI estimate based on the results of laboratory core studies and, therefore, the proposed approach can be used when performing work related to 3D modeling.

Population exposure to flooding in Small Island Developing States under climate change

Abstract Estimates of current and future population exposure to both coastal and inland flooding do not exist consistently in all Small Island Developing States (SIDS), despite these being some of the places most at risk to climate change. This has primarily been due to a lack of suitable or complete data. In this paper, we utilise a ∼30 m global hydrodynamic flood model to estimate population exposure to coastal and inland flood hazard in all SIDS under present day, as well as under low, intermediate, and very high emissions climate change scenarios (SSP1-2.6, SSP2-4.5 and SSP5-8.5). Our analysis shows that present day population exposure to flooding in SIDS is high (19.5% total population: 100 year flood hazard), varies widely depending on the location (3%–66%), and increases under all three climate scenarios—even if global temperatures remain below 2 °C warming (range in percentage change between present day and SSP1-2.6: −4.5%–44%). We find that levels of flood hazard and population exposure are not strongly linked, and that indirect measures of exposure in common vulnerability or risk indicators do not adequately capture the complex drivers of flood hazard and population exposure in SIDS. The most exposed places under the lowest climate change scenario (SSP1-2.6) continue to be the most exposed under the highest climate change scenario (SSP5-8.5), meaning investment in adaptation in these locations is likely robust to climate scenario uncertainty.

IMPROVING METHODS FOR PREDICTING THE STRUCTURE OF GAS-LIQUID FLOW IN HORIZONTAL PIPES

Analysis of existing research on the hydrodynamics of two-phase mixtures allows us to trace the main trends in the development of engineering calculation methods, as well as identify the most promising approaches for developing algorithms for predicting the patterns of gas-liquid flows in horizontal pipes. Predicting the patterns of two-phase flows is necessary to solve a number of applied problems related to the design of field pipeline systems, monitoring of operational parameters during the transportation of well products, calculation of hydraulic pressure drop in pipes, etc. Conventionally, in creating methods for predicting flow regimes in horizontal pipes, there are stages based on empirical approaches, mechanistic modeling and unification of hydrodynamic criteria for assessing the processes of patterns transformations of two-phase flows. Approaches based on the unification of hydrodynamic models of gas-liquid flows are noted as promising directions in the development of hydrodynamic forecasting criteria. The principles of unification consist in bringing to uniformity a mathematical apparatus capable of predicting all possible patterns of gas-liquid flow in vertical, inclined and horizontal pipes based on known volumetric flow rates of liquid and gas. The article proposes the improvement of known unification approaches in the development of criteria for predicting the annular and dispersed-bubble patterns of gas-liquid flow in field pipes. The verification of the obtained algorithms for pattern prediction of annular and dispersed-bubble modes of horizontal gas-liquid flow was carried out.

Response of tidal dynamics and shear fronts to topographic changes in the Yellow River Delta

In recent years, the position of the Yellow River Estuary (YRE) entrance has changed frequently, and human activities such as land reclamation have contributed to the transformation of the deltaic topography. These combined factors have resulted in altered hydrodynamics and tidal shear fronts (TSFs) in the surrounding sea area. However, there are few studies on the characteristics of the TSFs before and after diversion, so this paper establishes a hydrodynamic model based on the Finite Volume Coastal Ocean Model (FVCOM) for the years 2005, 2014, and 2020 and analyzes the characteristics of the changes in the tidal currents and the TSFs before and after diversion and the long-term evolution trends. The results reveal that the M2 amphidromic point near the YRE shifted eastward by 4.9 km from 2005 to 2014 and migrated southeastward by 6.8 km between 2014 and 2020. Additionally, significant changes were observed in the maximum and residual currents within the active mouth (AM), the old Qing 8 (Q8) channel, the old QingShuiGou (QSG) channel, and the southeastern region. Notably, the residual currents exhibit vertical fronts with substantial current velocity differences across the slopes. After the diversion of the YRE, the northern TSFs disappeared. The TSFs in the AM gradually shifted landward, while the TSFs in the southeastern region shifted offshore. In the vertical direction, the frontal centerlines of the TSFs gradually moved offshore from top to bottom. The intensity of the TSFs at the same latitude was positively correlated with the offshore distance. Generally, steeper slopes were associated with larger bottom stress gradients, which in turn corresponded to stronger TSFs.

Dam Breach Analysis and Damage Assessment of Nova Kakhovka Dam using Satellite data and 1D and 2D Hydrodynamic Modeling

Dam Breach Analysis and Damage Assessment of Nova Kakhovka Dam using Satellite data and 1D and 2D Hydrodynamic Modeling

Hydraulic Design and CFD-Based Parametric Study for Optimizing Centrifugal Pump Impeller Performance

Centrifugal pumps are extensively utilized across various industries, including water supply, agriculture, and energy, where they consume significant amounts of electricity. As demands for energy efficiency and reduced operating costs increase, enhancing pump efficiency has become crucial. This study focuses on optimizing the pump impeller geometry, which plays a vital role in minimizing energy losses. A hydraulic and hydrodynamic model was developed, alongside a parametric study based on numerical simulations (CFD), to analyze the influence of geometric parameters—specifically the angles and shapes of the blade’s inlet and outlet edges—on energy losses and hydraulic efficiency. The study utilized experimental data provided by the manufacturer for model verification. The results revealed that Ivanovsky’s method displayed deviations in the blade width at the leading edge and trailing edge of 25% and 43%, respectively, while Spiridonov’s method indicated deviations of 13% in the outer diameter D2 and 27.5% in the blade width at the trailing edge. In contrast, the combined method proposed by the authors achieved high accuracy, with deviations under 9%. Additionally, parametric analysis identified two key parameters affecting the pump efficiency: the angle of the trailing edge and its shape. These findings underscore the necessity of optimizing the blade geometry to enhance the performance and energy efficiency of centrifugal pumps.

Development and performance of a high-resolution surface wave and storm surge forecast model: application to a large lake

Abstract. A real-time forecast model of surface hydrodynamics in Lake Ontario (Coastlines-LO) was developed to automatically predict storm surges and surface waves. The system uses a dynamically coupled Delft3D–SWAN model with a structured grid to generate 48 h predictions for the lake that are updated every 6 h. The lake surface is forced with meteorological data from the High Resolution Deterministic Prediction System (HRDPS). The forecast model has been running since May 2021, capturing a wide variety of storm conditions. Good agreement between observations and modelled results is achieved, with root mean squared errors (RMSEs) for water levels and waves under 0.02 and 0.26 m, respectively. During storm events, the magnitude and timing of storm surges are accurately predicted at nine monitoring stations (RMSE <0.05 m), with model accuracy either improving or remaining consistent with decreasing forecast length. Forecast significant wave heights agree with observed data (1 %–12 % relative error for peak wave heights) at four wave buoys in the lake. Coastlines-LO forecasts for storm surge prediction for two consecutive storm events were compared to those from the Great Lakes Coastal Forecasting System (GLCFS) to further evaluate model performance. Both systems achieved comparable results with average RMSEs of 0.02 m. Coastlines-LO is an open-source wrapper code driven by open data and has relatively low computational requirements compared to GLCFS, making this approach suitable for forecasting marine conditions in other coastal regions.

Probing trade-off between critical size and velocity in cold-pray: An atomistic simulation

The detailed mechanism of bonding in the cold spray process has remained elusive for both experimental and theoretical parties. Adiabatic shear instability and hydrodynamic plasticity models have been so far the most popular explanations. Here, using molecular dynamics simulation, we investigate their validity at the nanoscale. The present study has potential applications in the fabrication of ultrathin layers in the electronics industry. For this aim, we considered Ti nanoparticles of different diameters and Si substrates of different orientations. It is shown that very high spray velocities are required for a jet to be observed at the nanoscale. We propose a method for thermostating the substrate that enables utilizing high spray velocities. For the first time, we demonstrate an oscillatory behavior in both the normal and radial stress components within the substrate that can propagate into the particle. We have shown that neither the adiabatic shear instability model nor the hydrodynamic plasticity model can be ignored at the nanoscale. In addition, the formation of a low-resistance titanium silicide proper for electronic application is illustrated.

A high-performance ray tracing particle tracking model for the simulation of microplastics in inland and coastal aquatic environments

In this study, we present a high-performance Particle Tracking Model (PTM) designed for simulating any type of particles, with a focus on microplastics. The PTM is efficient compared to existing models, parallelized, and utilizes a ray tracing algorithm incorporating both ray reflection and ray refraction in order to traverse particles as well as find the location of each particle over three-dimensional unstructured grids. Various numerical corrections are implemented in the model to address computational round-off errors and discontinuities in the water surface level of the input hydrodynamic models. To increase the accuracy of the model, partially reflective boundary conditions are imposed as well as the capability to simulate microplastics beaching and washout in very shallow areas or dry computational cells. Several tests are conducted to study the performance, scalability, and accuracy of the model. The proposed model is tested with over 3.88 billion double-precision particles on three-dimensional computational grids with up to approximately one million cells. The tests show that the ray tracing approach is efficient, achieves over 17× faster runtime, and offers greater accuracy compared to using an auxiliary grid for particle location finding. For larger timesteps, the ray tracing PTM with refraction shows improved accuracy compared to the ray tracing PTM without refraction. The model's capabilities are tested in a real-world case study over the Saguenay Fjord, Quebec, Canada. The model is utilized to reproduce the paths of five surface drifters. A second numerical test is conducted in the Fjord and high particle concentration areas are identified.

A Novel Input Schematization Method for Coastal Flooding Early Warning Systems Incorporating Climate Change Impacts

Coastal flooding poses a significant threat to coastal communities, adversely affecting both safety and economic stability. This threat is exacerbated by factors such as sea level rise, rapid urbanization, and inadequate coastal infrastructure, as noted in recent climate change reports. Early warning systems (EWSs) have proven to be effective tools in coastal planning and management, offering a high cost-to-benefit ratio. Recent advancements have integrated operational numerical models with machine learning techniques to develop near-real-time EWSs, leveraging data obtained from reputable databases that provide reliable hourly sea-state and sea level data. Despite these advancements, a stepwise methodology for selecting representative events, akin to wave input reduction methods used in morphological modeling, remains undeveloped. Moreover, existing methodologies often overlook the significance of compound extreme events and their potential increased occurrence under climate change projections. This research addresses these gaps by introducing a novel input schematization method that combines efficient hydrodynamic modeling with clustering algorithms. The proposed methodοlogy, implemented in the coastal area of Pyrgos, Greece, aims to select an optimal number of representative sea-state and water level combinations to develop accurate EWSs for coastal flooding risk prediction. A key innovation of this methodology is the incorporation of weights in the clustering algorithm to ensure adequate representation of extreme compound events, also taking into account projections for future climate scenarios. This approach aims to enhance the accuracy and reliability of coastal flooding EWSs, ultimately improving the resilience of coastal communities against imminent flooding threats.

Targeting GSDME-mediated macrophage polarization for enhanced antitumor immunity in hepatocellular carcinoma.

Despite the notable efficacy of anti-PD1 therapy in the management of hepatocellular carcinoma (HCC) patients, resistance in most individuals necessitates additional investigation. For this study, we collected tumor tissues from nine HCC patients receiving anti-PD1 monotherapy and conducted RNA sequencing. These findings revealed significant upregulation of GSDME, which is predominantly expressed by tumor-associated macrophages (TAMs), in anti-PD1-resistant patients. Furthermore, patients with elevated levels of GSDME+ macrophages in HCC tissues presented a poorer prognosis. The analysis of single-cell sequencing data and flow cytometry revealed that the suppression of GSDME expression in nontumor cells resulted in a decrease in the proportion of M2-like macrophages within the tumor microenvironment (TIME) of HCC while concurrently augmenting the cytotoxicity of CD8 + T cells. The non-N-terminal fragment of GSDME within macrophages combines with PDPK1, thereby activating the PI3K-AKT pathway and facilitating M2-like polarization. The small-molecule Eliprodil inhibited the increase in PDPK1 phosphorylation mediated by GSDME site 1. The combination of Eliprodil and anti-PD1 was effective in the treatment of both spontaneous HCC in c-Myc + /+;Alb-Cre + /+ mice and in a hydrodynamic tail vein injection model, which provides a promising strategy for novel combined immunotherapy.

Prediction of Sediment Transport and Deposition in the Stone Buddha Temple Reservoir Based on HD and ST Bidirectional Coupling Model

Reservoirs deliver vital ecological services, including water storage and drainage. However, these functions are increasingly compromised by the dual pressures of climate change and human activities. Among the most pressing concerns is reservoir sedimentation, highlighting the urgency of investigating hydrodynamic sediment scouring. This study focuses on the plain reservoirs of Liaoning Province, using the Shifo Temple Reservoir as a case study. An optimized sediment scouring scheme was developed based on the reservoir’s hydrodynamic characteristics to improve water and sediment management. A coupled hydrodynamic and sediment transport (ST) model was constructed to simulate runoff dynamics and sediment distribution within the Liao he River Basin, while the MIKE21 model was applied to simulate the interaction between the hydrodynamics and sediment transport. The study analyzed groundwater dynamics across different runoff scenarios, seasons, and representative years, offering a scientific foundation for optimizing water and sediment allocation strategies. The results demonstrated a strong correlation between simulated and observed data during validation, confirming the accuracy of the hydrodynamic simulations. Utilizing the coupled HD and ST modules, the study proposed a sediment transfer scheme. The analysis revealed that flow rates between 165 and 190 m3/s significantly enhance sediment scouring in the long term (2029–2039) compared to the short term (2024–2029), effectively reducing sedimentation, minimizing deposition length, and lowering silt removal costs. The findings offer critical insights for predicting reservoir evolution and conducting risk assessments, thereby contributing to the sustainable management and ecological restoration of water systems in Liaoning Province.

Embankment Breach Simulation and Inundation Mapping Leveraging High-Performance Computing for Enhanced Flood Risk Prediction and Assessment

Abstract. Embankment breaches represent significant hazards to communities and infrastructure, precipitating catastrophic flood occurrences. The precise prediction of floods and understanding the scope of inundation stemming from embankment failures are imperative for effective disaster preparedness and response. This research delves into a case study on simulating embankment breaches to evaluate the extent of flooding. Leveraging advanced hydrodynamic models validated through high-performance computing (HPC) systems, and integrating real-time data assimilation, we aim to improve accuracy in flood forecasting. The study endeavours to bolster flood risk management by furnishing detailed inundation maps and insights into embankment breach dynamics, thereby facilitating enhanced preparedness and response strategies. Our findings reveal that simulations conducted on multicore processors offer superior performance compared to single-core setups, yielding enhanced result accuracy and providing administrators with increased lead time. It unlocks high-resolution simulations for intricate basin details, explores a wider range of flood scenarios quickly, and allows for efficient ensemble modelling to assess model uncertainty. Through HPC utilization, we can harness high-resolution digital elevation models (DEMs) for 2D-hydrodynamic modelling, enabling rapid assessment of water spread resulting from embankment breaches within a mere 20-minute timeframe, a significant improvement from the previous 3–4 hours duration.

Hydrodynamic Modeling of Khenifiss Coastal Lagoon, Southern Atlantic Coast of Morocco: Implications for Sediment Infilling

Hydrodynamic Modeling of Khenifiss Coastal Lagoon, Southern Atlantic Coast of Morocco: Implications for Sediment Infilling

Analysis of Downstream Sediment Transport Trends Based on In Situ Data and Numerical Simulation

This study conducted an in-depth analysis of the sediment dynamics in the lower reaches of the Changhua River and its estuary on Hainan Island. Through field collection of topographic data and sediment sampling, combined with advanced computational techniques, the study explored the transport pathways and depositional patterns of sediments. The grain size trend analysis (GSTA) method was utilized, in conjunction with the Flemming triangle diagram method, to classify the dynamic environment of the sediments. Furthermore, hydrodynamic modeling results were integrated to further analyze the transport trends of the sediments. The study revealed that the sediment types in the research area are complex, primarily consisting of gravelly sand and sandy gravel, indicating a generally coarse sedimentary environment in the region. The sediments in the lower reaches of the Changhua River generally transport towards the south and southwest (in the direction of Beili Bay). The net sediment transport directions inferred from the GSTA model are largely consistent with the Eulerian residual flow patterns, especially in the offshore area, where discrepancies are observed in the nearshore zone. The nearshore transport is influenced by the combined effects of alongshore currents, residual flows, and river inputs, while the offshore transport exhibits a shift from the northwest to southwest directions, reflecting the regional circulation patterns.

Local univalence versus stability and causality in hydrodynamic models

Our primary goal is to compare the analytic properties of hydrodynamic series with the stability and causality conditions applied to hydrodynamic modes. Analyticity, in this context, serves as a necessary condition for hydrodynamic series to behave as a univalent function. Stability and causality adhere to physical constraints, ensuring that hydrodynamic modes neither exhibit exponential growth nor travel faster than the speed of light. Through an examination of various hydrodynamic models, such as the Müller–Israel–Stewart (MIS) and the first-order hydro models like the BDNK (Bemfica–Disconzi–Noronha–Kovtun) model, we observe no new restrictions stemming from the univalence limits in the shear channels. However, local univalence is maintained in the sound channel of these models despite the global divergence of the hydrodynamic series. Notably, differences in the sound equations between the MIS and BDNK models lead to distinct limits. The MIS model’s sound mode remains univalent at high momenta within a specific transport range. Conversely, in the BDNK model, the univalence of the sound mode extends to intermediate momenta across all stable and causal regions. Generally, the convergence radius is independent of univalence, and the given dispersion relation predominantly influences their correlation. For second-order frequency dispersions, the relationship is precise; i.e., within the convergence radius, the hydro series demonstrates univalence. However, with higher-order dispersions, the hydro series is locally univalent within certain transport regions, which may fall within or outside the stable and causal zones.

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.

A probabilistic coral rubble mechanical instability model applied with field observations from the Great Barrier Reef

Unstable coral rubble hinders coral recruitment and recovery of coral reefs after damage from cyclones and bleaching events. If coral rubble remains unstable under typical everyday environmental conditions, areas of coral rubble will not be able to recover. Evaluating the probability of rubble instability over regional scale reef systems can assist the optimization of coral reef restoration efforts. Currently, robust and verified models for such applications do not exist. This paper presents a comprehensive assessment method to predict the probability of coral rubble instability, which combines a fluid-structural interaction approach with a statistical regional wave climate model. The hydrodynamic model employs non-linear wave theory to determine near-bed velocity, pressure gradients, and the corresponding drag and inertia forces acting on the coral rubble. The instability model assesses when overturning or sliding forces exceed resisting forces, considering thousands of combinations of different coral sizes and densities to calculate the proportion of instability under a given wave forcing. The model was calibrated and validated using prior laboratory experiments as reported by Kenyon et al. (2023b). The hydrodynamic and instability models use an extensive dataset of non-cyclonic wave climates (hindcast from over 30 years of wind measurements) specific to the region around Heron Reef, Great Barrier Reef, Australia, enabling a comprehensive evaluation of the probability of rubble instability in this area. Results indicate that the overall probability of rubble instability reaches 0.74 in water depths less than 2 meters (typical of reef crests or reef flats), while it declines to below 0.21 at a depth of 12 meters (typical deeper parts of the fore reef). Coral rubble on reef crests near Heron Reef, which are sheltered by surrounding formations, demonstrates low probability of instability. Thus, coral rubble instability is influenced by both its specific location within the reef and the position of the reef relative to other nearby reefs. By integrating the rubble instability model with non-cyclonic wave climate data, a map of the probability of rubble instability was generated for eight reefs in the Capricorn and Bunker Group (CBG). This map provides valuable guidance for coral reef restoration efforts, significantly reducing the need for extensive field-based data.