Article
Astronomy & Astrophysics
K. Bora, R. Bhattacharyya, P. K. Smolarkiewicz
Summary: This study extends the computational model EULAG-MHD by incorporating Hall magnetohydrodynamics (HMHD) to explore fast magnetic reconnection at the ion inertial length scale. The results show that magnetic reconnections onset significantly earlier in HMHD simulations, leading to the development of magnetic flux ropes and tubes in three-dimensional evolution.
ASTROPHYSICAL JOURNAL
(2021)
Article
Geosciences, Multidisciplinary
M. A. Veerman, B. J. H. van Stratum, C. C. van Heerwaarden
Summary: This study presents simulations of cumulus convection over land using a coupled ray tracer, which provides realistic in-cloud heating rates and global horizontal irradiance fields. The performance of the ray tracer is enabled by the power of graphics processing unit computing and techniques for accelerating data lookup and ray tracer convergence. The results show that the simulated cloud evolution is insensitive to ray tracer convergence, and that simulations with a coupled ray tracer produce surface irradiance patterns resembling observations and strongly influencing cloud evolution through locally enhanced surface heat fluxes.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Environmental Sciences
Jule Radtke, Thorsten Mauritsen, Cathy Hohenegger
Summary: The response of shallow trade cumulus clouds to global warming is influenced by resolution, with higher resolution leading to a near-zero feedback. Cloud cover reduction has a positive shortwave cloud feedback, while cloud thickening acts as a compensating feedback that is largely resolution independent. Storm-resolving models may exaggerate the trade wind cumulus cloud feedback, suggesting the need for refinement in modeling techniques.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Engineering, Marine
C. Testa, F. Porcacchia, R. Muscari, L. Greco
Summary: The aim of this research is to gain a physical understanding of the main noise generating mechanisms related to vorticity and turbulence downstream the disk of a marine propeller in open water. Through the application of acoustic analogy and detached eddy simulation, the study investigates the correlation between acoustic signatures and wake evolution, as well as the effects of turbulence noise and vorticity-driven phenomena. The results show that turbulence is the most significant source of propeller noise, while vorticity effects are only important in a narrow region surrounding the propeller.
Article
Multidisciplinary Sciences
Christopher Klose, Felix Buettner, Wen Hu, Claudio Mazzoli, Kai Litzius, Riccardo Battistelli, Ivan Lemesh, Jason M. Bartell, Mantao Huang, Christian M. Guenther, Michael Schneider, Andi Barbour, Stuart B. Wilkins, Geoffrey S. D. Beach, Stefan Eisebitt, Bastian Pfau
Summary: Nanoscale magnetic fluctuations are observed beyond conventional resolution limits using coherent correlation imaging, allowing for the study of previously inaccessible magnetic phenomena. The method utilizes Fourier space analysis and an iterative hierarchical clustering algorithm to achieve high spatial and temporal resolution.
Article
Engineering, Chemical
Linna Jin, Yuhui Cao
Summary: This study applied the improved delayed detached-eddy simulation (IDDES) method to predict turbulent mixing in a confined impinging-jet mixer. The results showed good agreement with experimental data and provided insights on the coherent structures and their effects on turbulence statistics and mixing efficiency.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
H. Dashtpeyma, B. J. MacVicar
Summary: Pool-riffle units are natural topographical elements of rivers. This study uses Large Eddy Simulations to investigate the dynamics of flow over straight riffles and proposes a physical mechanism for the observed high near-bed velocities. The results provide a novel explanation for near-bed high velocity flow observations in natural pool-riffles and reveal the significance of turbulent shear stresses in the head of a pool.
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
(2023)
Article
Astronomy & Astrophysics
Maxence Lefevre, Martin Turbet, Raymond Pierrehumbert
Summary: Research findings suggest that while cloud albedo increases with increasing stellar flux on tidally locked planets, the weak cloud feedback is attributed to transient aggregation of convection leading to low cloud cover.
ASTROPHYSICAL JOURNAL
(2021)
Article
Geosciences, Multidisciplinary
Mengrong Ding, Hailong Liu, Pengfei Lin, Aixue Hu, Yao Meng, Yiwen Li, Kexiu Liu
Summary: The performance of eddy-resolving global ocean-sea ice models in simulating mesoscale eddies is evaluated, revealing an overestimation of energy intensity in eddy-rich regions and an underestimation of eddy kinetic energy in eddy-poor regions.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
Klaudia Dradrach, Michal Zmyslony, Zixuan Deng, Arri Priimagi, John Biggins, Piotr Wasylczyk
Summary: Researchers demonstrate the use of light-driven pumping for small-scale manipulation of microlitre volumes of liquid using a liquid crystal elastomer strip. Optofluidics, which utilizes light for power and control, offers the potential for small, self-contained microfluidic devices that are more efficient and simpler to operate.
NATURE COMMUNICATIONS
(2023)
Article
Mechanics
Ming Yu, Dong Sun, QingQing Zhou, PengXin Liu, XianXu Yuan
Summary: In this study, we used direct numerical simulation databases to investigate the evolution of turbulent statistics and coherent structures in hypersonic turbulent boundary layers subjected to oblique shock waves. We found that large-scale structures are amplified within the interaction zone and gradually decay downstream, leading to discrepancies between the predictions of Reynolds-Averaged Navier-Stokes simulations and the actual flow behavior. To address this issue, we proposed refining the model parameters as functions of wall pressure and other flow quantities, leading to improved accuracy in predicting various flow properties downstream of the interaction zone.
Article
Thermodynamics
Kristian Ronnberg, Christophe Duwig
Summary: In this study, heat transfer arising from an impinging jet at a Reynolds number of 5000 was investigated through Large Eddy Simulation (LES). The heat transfer was found to be distributed according to a gamma distribution, and was decomposed using proper orthogonal decomposition (POD) and extended proper orthogonal decomposition (EPOD). The results showed that distinct flow features were associated with low order heat transfer modes, with dominant modes identified as ring-like vortex structures. Reconstruction of the heat transfer field revealed radially outward moving structures with a phase velocity of 0.23 U-b.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Engineering, Civil
Pengcheng Zou, Shuyang Cao, Jinxin Cao
Summary: In this study, the spanwise correlation and coherent structure of separated flow around a rectangular cylinder with a side ratio of B/D = 5 were numerically investigated using Large Eddy Simulation (LES) at Reynolds number Re = 22,000. The results showed the existence of a spanwise coherent flow structure associated with longitudinal vortices, with a wavelength of around 1.4D. A spanwise length of 3D was found to be sufficient in eliminating the influence of the spanwise coherent flow structure on the global aerodynamic parameters. The spanwise correlations of sectional forces and surface pressures decayed with increasing spanwise distance, and a finer spanwise resolution resulted in decreased spanwise correlations within the investigated range. The results also emphasized the need to consider multiple interacting factors, such as numerical method, three-dimensional grid discretization, and turbulence model, when selecting the spanwise resolution.
JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS
(2022)
Article
Astronomy & Astrophysics
R. T. Gangadhara, J. L. Han, P. F. Wang
Summary: Based on the tangent model, a collective plasma radio emission model for radio pulsars has been developed, predicting correlation between sign reversal circular polarization, polarization angle swing, and brightness temperature. Numerical estimations show enhanced radio wave flux when resonance between radio and plasma waves occurs.
ASTROPHYSICAL JOURNAL
(2021)
Article
Construction & Building Technology
Abdillah Alwi, Mohd Faizal Mohamad, Naoki Ikegaya, Azli Abd Razak
Summary: The study investigates the influence of different eave designs on flow structure and turbulence characteristics within and above a 2D semi-open street canyon using large eddy simulation (LES). The results show that the size of vortices changes with the length and positioning of the eaves, and the turbulence statistics are strongly dependent on eave dimension and position. The presence of eaves reduces turbulence intensities and Reynolds stress by attenuating the penetration of above flow into the street canyon. The spatially-averaged profiles exhibit a dependence on the total length of eaves rather than the position of individual eave.
BUILDING AND ENVIRONMENT
(2023)
Article
Environmental Sciences
Shanshan Deng, Junqiang Xia, Meirong Zhou, Zhiwei Li, Guanglei Duan, Jian Shen, Koen Blanckaert
Summary: This study investigates the hydrodynamics in two consecutive sharp bends of the Middle Yangtze River and finds that a reduced-order model can accurately resolve the secondary flow strength and continuous flow redistribution, showing that flow redistribution is primarily controlled by planimetric changes in curvature and topographic steering.
WATER RESOURCES RESEARCH
(2021)
Article
Geosciences, Multidisciplinary
Liqun Lyu, Mengzhen Xu, Zhaoyin Wang, Yifei Cui, Koen Blanckaert
Summary: Through an investigation of gullies along the Daheba River, it was found that debris flows are influenced by Z(E) topography, with sediment abundantly available from steep erodible gully banks. Debris flows consist of a head and a body, and as the gully drainage area increases, Z(E) and debris flow frequency initially increase before decreasing.
Article
Engineering, Civil
Mete Koken, Ismail Aydin, Serhan Ademoglu
Summary: Piano Key Weir (PKW) is a type of overflow weir with improved discharge capacity, making it an attractive alternative for rehabilitating existing spillways. Various geometrical parameters' effects on discharge capacity are studied through experimental and numerical approaches, with numerical solutions used to create dimensionless expressions for the design and optimization of PKW structures.
JOURNAL OF HYDRO-ENVIRONMENT RESEARCH
(2022)
Article
Computer Science, Interdisciplinary Applications
Martin Hasenhuendl, Koen Blanckaert
Summary: Morphometric characteristics play a crucial role in the classification and modeling of fluvial systems. A simple-to-use Matlab script is presented for determining the important morphometric characteristics of subaerial, subaquatic and extra-terrestrial rivers, channels, and canyons. This script provides an efficient tool for analyzing digital elevation models (DEMs) and will contribute to the understanding of poorly understood subaquatic systems and the largest canyon and channel systems on Earth.
COMPUTERS & GEOSCIENCES
(2022)
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
Environmental Sciences
H. Shi, M. E. Negretti, J. Chauchat, K. Blanckaert, U. Lemmin, D. A. Barry
Summary: This study examines the characteristics of three-dimensional plunging flow patterns of hyperpycnal river inflow into lakes and oceans. The researchers found that the inflow densimetric Froude number and the bed slope of the receiving water body are the dominant control parameters. They also observed that the hydrodynamics of laterally unconfined plunging are fundamentally different from confined plunging, with the hyperpycnal plume forming a triangle on the surface and exhibiting increased entrainment coefficient. The study highlights the importance of understanding the dynamics of hyperpycnal inflow for better management of lakes and oceans.
WATER RESOURCES RESEARCH
(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
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
Water Resources
Violaine Piton, Frederic Soulignac, Ulrich Lemmin, Benjamin Graf, Htet Kyi Wynn, Koen Blanckaert, David Andrew Barry
Summary: River inflows have a significant impact on lake water quality, contributing to the input of sediments, nutrients, and contaminants. In Lake Geneva, the interaction between the Rhone River plume and lake waters was studied, revealing the dynamics of nearfield hydro-sedimentation. The study found that the river inflow intruded into the lake as a lateral unconfined interflow and mainly spread laterally due to entrainment of ambient water.
FRONTIERS IN WATER
(2022)