Article
Geosciences, Multidisciplinary
Kaili Zhang, Zheng Gong, Kun Zhao, Keyu Wang, Siqi Pan, Giovanni Coco
Summary: The study investigates the stability of overhanging riverbanks through laboratory experiments and numerical simulations. Results show that flow infiltration leads to decreased soil shear strength and shear failure. The distance of the failure surface can be characterized by twice the width of the overhanging block.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2021)
Article
Water Resources
Mingyang Wang, Eldad Avital, Theodosios Korakianitis, John Williams, Kaiming Ai
Summary: This study investigates the hydrodynamics in a bending channel with aquatic vegetation, finding that an increase in curvature ratio leads to a shift in the main circulation cell and thalweg's location, while an increase in vegetation density may result in a decrease in the dominant shedding frequency. The study also proposes a new dimensionless frequency number, St(p)root SVF/root N, which remains nearly constant for each case series.
ADVANCES IN WATER RESOURCES
(2021)
Article
Water Resources
Milad Pourvahedi, Khosrow Hosseini, Sayed-Farhad Mousavi, Kiarash Geranmayeh
Summary: The confluence of rivers is a vital phenomenon for irrigation and water transmission networks. Investigating the bed morphology at the junction is important due to the complexities and risks it poses. This research aims to study the effect of geometric and hydraulic parameters on the bed morphology at intersections using SSIIM2.
APPLIED WATER SCIENCE
(2023)
Article
Engineering, Geological
Kendra White, Yuntong She, Wenming Zhang
Summary: This study compared different methods for estimating bed shear stress and found that the turbulent kinetic energy method with newly calibrated proportionality constants was the most accurate in representing the local bed shear stress on geobags. The Reynolds stress method was relatively unaffected by changes to the geobags' shape and measurement locations, but inadequately represented the local bed shear stress. The Patel method and universal law of the wall method failed to accurately represent bed shear stress in rough bed cases.
GEOTEXTILES AND GEOMEMBRANES
(2022)
Article
Geosciences, Multidisciplinary
Alex Garces, Gerardo Zegers, Albert Cabre, German Aguilar, Aldo Tamburrino, Santiago Montserrat
Summary: This article presents a workflow to model the response of the Crucecita Alta alluvial fan in Chile during an extreme storm event. By aggregating five different debris flow deposits and associating them with four flow surges, we demonstrate the significance of the alluvial fan in controlling the connectivity between tributaries and the main river.
NATURAL HAZARDS AND EARTH SYSTEM SCIENCES
(2022)
Article
Engineering, Chemical
Yanlin Zhao, Yudong Yan, Xueyao Zhou, Jun Yao, Chi-Hwa Wang
Summary: This study used numerical simulation to investigate the effect of electrostatic field on particle behavior and erosion in a turbulent circular-sectioned bend. Results showed that the electrostatic field does affect particle motion, with the impact angle increasing at a lower rate with higher electrostatics and higher air flow rate. Additionally, erosion rate increases with air flow rate but decreases with the occurrence of electrostatics, and the effect of electrostatics on erosion decreases with increasing air flow rate.
ADVANCED POWDER TECHNOLOGY
(2021)
Article
Engineering, Mechanical
Prasun Dutta, Himadri Chattopadhyay, Nityananda Nandi
Summary: This paper presents a numerical study on the turbulent flow in a 90 deg pipe bend. It demonstrates that the k-epsilon model performs reasonably well for pipe flows with curvature. The influence of Reynolds number and bend curvature ratio on turbulent flow parameters is investigated. The results show that bend curvature strongly affects the turbulent flow characteristics, while no high Reynolds number dependency is observed within the range studied. This study provides cost-effective insights for the design and development of 90 deg pipe bends at high Reynolds number regimes.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2022)
Article
Thermodynamics
P. Hu, M. Yu
Summary: The helical flow in open-channel bends leads to the redistribution of bed shear stress and roughness coefficient, affecting sediment transport and riverbed evolution. A 3D numerical simulation of a sharp bend was conducted, revealing the occurrence of high bed shear stress in the inner bank region, which gradually shifted outward. The contributions of crossstream circulation and cross-flow to downstream bed shear stress were found to be of the same magnitude, with an overall contribution rate of 20% for cross-stream circulation.
JOURNAL OF APPLIED FLUID MECHANICS
(2023)
Article
Mechanics
Victor Dupuis, Frederic Y. Moulin, Olivier Eiff
Summary: The experiments were conducted in an open-channel flow with a smooth section and a section consisting of submerged or emergent cubes, resulting in a shear layer with large-scale Kelvin-Helmholtz structures. The analysis of the flow was performed using a double-averaging method, allowing for measurement of the velocity field in a large volume including the interstices between the cubes. The results showed that the loss of momentum towards the rough section had a similar magnitude to the loss through bed friction, and the lateral momentum flux was mainly caused by turbulent shear stress.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Environmental Sciences
K. B. J. Dunne, P. E. Arratia, D. J. Jerolmack
Summary: Cohesion is a crucial factor in determining erosion rates and morphodynamics of sediment deposits. A new instrument is introduced in this study that can measure the cohesion of submerged sediments, providing a convenient method for in situ measurements.
WATER RESOURCES RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Qiusong Chen, Hailong Zhou, Yunmin Wang, Daolin Wang, Qinli Zhang, Yikai Liu
Summary: Pipeline hydraulic transport is an efficient method for solid transportation, but erosion wear (EW) remains a major issue in tailings slurry pipeline systems, especially at bends. However, research in this area has been limited. This study uses numerical simulations to investigate the effects of inlet velocity, particle size, and bend angle on EW at the bend. The results show that the maximum EW rate increases exponentially with inlet velocity and particle size, and it first increases and then decreases with the increase in bend angle within the studied ranges. The sensitivity analysis indicates that particle size has the highest impact on the maximum EW rate, followed by inlet velocity and bend angle.
INTERNATIONAL JOURNAL OF MINERALS METALLURGY AND MATERIALS
(2023)
Article
Engineering, Chemical
Ram Krishna, Niranjan Kumar, Pankaj Kumar Gupta
Summary: This study implements erosion models based on the energy approach to predict erosion of bends in pipelines transporting slurry with moderate-to-high solids concentration. Numerical modeling and experimental validation show that the erosion model accurately predicts erosion at the bend walls and that erosion wear is reduced when slurry is transported at higher solids efflux concentration with velocities close to the deposition (or critical) velocity.
Article
Engineering, Civil
Jiajia Pan, Hung Tao Shen, Nian-Sheng Cheng
Summary: Experimental studies have proposed various empirical equations for mean bed and wall shear stresses in smooth rectangular open channels. By modifying the gravity force parameter used for dimensionalizing shear stresses to include width and wetted-perimeter, new dimensionless equations have been derived that accurately predict shear stresses and the wall/bed shear force ratio. These equations also provide new relationships for bed and wall friction factors.
JOURNAL OF HYDRAULIC RESEARCH
(2021)
Article
Engineering, Chemical
Tanuj Joshi, Om Parkash, Gopal Krishan, Anarghya A. Murthy
Summary: Slurry transportation through a pipeline is complex and requires high suspension stability and energy to deliver solid materials. Most studies only focus on basic parameters for uni-model slurry systems, ignoring the effects of multiple particles. This study investigates the characteristics of bi-model slurry flow through a horizontal bend, revealing that a slurry mixture ratio of 65:35 is the most efficient for long-term transportation due to a significant pressure drop.
Article
Environmental Sciences
Yi Xiao, Jie Liu, Cuicui Qin, Fang Xu
Summary: An improved 2D depth-averaged model is proposed for predicting hydrodynamic, sediment transport, and morphological adjustment. By considering the phase lag effect of the secondary flow and the influence of selective sorting, the model can accurately predict the flow patterns and bed evolution in river bends.
ENVIRONMENTAL MODELING & ASSESSMENT
(2022)
Article
Mechanics
Mete Koken, George Constantinescu
Summary: The study investigates the flow structure around a rectangular array of emerged cylinders in an open channel, focusing on flow and turbulence behaviors both inside and downstream of the array. The simulation results show the significant role played by coherent structures in sediment transport within the shear layer and near the array.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Civil
Hao Wu, Jie Zeng, George Constantinescu
Summary: A numerically-based approach was used to propose a modified formula for riprap size selection, taking into account the effects of bank curvature and floodplain width on apron design.
JOURNAL OF HYDRAULIC RESEARCH
(2021)
Article
Mechanics
Zhengyang Cheng, George Constantinescu
Summary: When two converging flows of unequal velocities and different flow directions come into contact, large-scale coherent structures are generated, including Kelvin-Helmholtz vortices and streamwise-oriented vortical cells. The mixing layer formed in this process affects flow, turbulence structure, and sediment entrainment mechanisms.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Civil
Sara Venuleo, Dubravka Pokrajac, Talia Tokyay, George Constantinescu, Anton J. Schleiss, Mario J. Franca
Summary: Based on the results of large eddy simulation, this study investigates the sensitivity of gravity current depth results to definition, the impact of density and velocity profile nonuniformity on coefficients in depth-averaged continuity and momentum equations, and the sensitivity of entrainment coefficient to current depth definition. The study shows that different definitions of current depth can lead to significantly different numerical results, and the entrainment coefficient is more sensitive to parameterization than the definition of current depth.
JOURNAL OF HYDRAULIC ENGINEERING
(2021)
Article
Environmental Sciences
Chenyu Jiang, George Constantinescu, Saiyu Yuan, Hongwu Tang
Summary: In this study, numerical techniques are used to investigate the flow dynamics and mixing at the asymmetric confluence between the Yangtze River and the Poyang Lake channel. The effects of density contrast between the confluent flows and its impact on the flow structure and thermal mixing are also examined. The study found that density contrast leads to lateral near-bed intrusions and strong tilting of the mixing interface boundaries, ultimately increasing mixing at large distances from the confluence apex.
ENVIRONMENTAL FLUID MECHANICS
(2023)
Article
Mechanics
Zhengyang Cheng, George Constantinescu
Summary: This study investigates the mixing process between two parallel streams of different velocities and densities. The results show that the lock-exchange-like flow plays a crucial role in mixing and sediment entrainment, especially when there is a significant density difference between the two streams.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Water Resources
Hao Wu, George Constantinescu
Summary: This study investigates the changes in flow structure, drag forces, sediment entrainment mechanisms, and dilution of filtered water jet with increasing angle of attack for freshwater mussels in rivers. The results show that increasing angle of attack leads to greater drag forces on the mussel shell, stronger flow circulation, and increased shear stresses near the mussel, indicating potential for local scouring.
ADVANCES IN WATER RESOURCES
(2022)
Editorial Material
Agricultural Engineering
Seyed M. Hajimirzaie, George Constantinescu, Xiaofeng Liu, Thorsten Stoesser, Kaveh Zamani
JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
A. N. Sukhodolov, O. O. Shumilova, G. S. Constantinescu, Q. W. Lewis, B. L. Rhoads
Summary: This article introduces a theory for the mixing dynamics of shallow flows at confluences, and verifies the theoretical predictions and transitional behavior between two mixing modes through dye visualizations in field experiments. According to the theoretical framework, the mixing interface can grow rapidly in one mode, even though flow curvature and shallowness restrict growth through advective and turbulent lateral exchange of momentum and bed friction. These findings provide insight into the importance of different flow structure modalities in controlling mixing at river confluences and contribute to understanding the role of confluences in contaminant dispersion in river systems.
Article
Engineering, Civil
Wenjun Zhang, Colin D. Rennie, Ioan Nistor
Summary: Forecasting the time development of scour depth at bridge pier foundations is essential for mitigating or avoiding potential bridge failures. This study categorizes existing models for bridge pier scour into semiempirical, empirical, and artificial intelligence models, and develops a new multigene genetic programming (MGGP) model for predicting temporal scour depth. Experimental data from previous studies and new physical modeling tests are used to evaluate the performance of existing models and the newly developed MGGP model. Results demonstrate that the MGGP model has superior prediction capability compared to existing empirical and mathematical models.
CANADIAN JOURNAL OF CIVIL ENGINEERING
(2023)
Article
Mechanics
Wen-Yi Chang, George Constantinescu
Summary: In this study, flow and turbulent structures generated by the interaction of forced incoming oscillatory flow with a circular, vertical cylinder are investigated using eddy-resolving simulations. The results show that detached eddy simulation (DES) predicts more accurately the amplification of the bed shear stress and the maximum magnitude of the bed shear stress compared with unsteady Reynolds-averaged Navier-Stokes simulations. High-Reynolds-number DES simulations reveal the changes in the wake vortex-flow regimes and the generation of other near-bed coherent structures in the wake during the oscillatory cycle.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Environmental Sciences
T. Lazzarin, G. Constantinescu, L. Di Micco, H. Wu, F. Lavignani, M. Lo Brutto, D. Termini, D. P. Viero
Summary: The present study investigates the impact of bed roughness on flow and turbulence structure around an isolated, partially-buried mussel. The results show that increasing bed roughness amplifies turbulence kinetic energy in the near-wake region and weakens the strength of the main downwelling flow.
WATER RESOURCES RESEARCH
(2023)
Article
Mechanics
Mete Koken, George Constantinescu
Summary: This paper discusses the influence of the submergence ratio on the flow and turbulence structure inside and around an array of solid rigid cylinders. The vertical shear layer developed between the top face of the array and the free surface significantly increases flow three-dimensionality and modifies the momentum exchange between the array and surrounding open water regions. Eddy-resolving simulations show that the flow characteristics and turbulence phenomena inside the array vary with different solid volume fractions and submergence ratios.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Green & Sustainable Science & Technology
Katelyn Kirby, Colin D. Rennie, Julien Cousineau, Sean Ferguson, Ioan Nistor
Summary: Hydrokinetic energy resource assessment is crucial for turbine placement and energy extraction. However, many assessments lack detailed investigation of flow variation and its impact on optimal turbine placement. This case study conducted in Quebec, Canada estimates the resource, identifies optimal turbine locations, and studies the impact of seasonal flow variation. The assessment highlights the importance of considering the entire flow field in hydrokinetic energy assessments. Field data collected with acoustic Doppler current profiler and GPS were used to generate, calibrate, and validate the hydrodynamic model.
Article
Geosciences, Multidisciplinary
Oleksandra O. Shumilova, Alexander N. Sukhodolov, George S. Constantinescu, Bruce J. MacVicar
Summary: This study presents a detailed dataset on the hydrodynamics of shallow wake flows behind solid and porous obstructions, collected in a field experimental campaign in a side branch of the Tagliamento River in Italy. The dataset includes 30 experimental runs and provides valuable information for studying flow dynamics, validating numerical models, and understanding the effects of driftwood accumulations on wake dynamics.
EARTH SYSTEM SCIENCE DATA
(2021)