Article
Construction & Building Technology
Bingchao Zhang, Hong Hu, Hideki Kikumoto, Ryozo Ooka
Summary: This study uses spectral proper orthogonal decomposition (SPOD) to analyze the impact of turbulence on natural ventilation in a building. The results show that turbulence produces two main ventilation routes: cross ventilation in the low-frequency region and single-sided ventilation in the high-frequency region. Additionally, the installation location of window casements has a significant influence on turbulence-induced ventilation.
BUILDING AND ENVIRONMENT
(2022)
Article
Acoustics
Weiqi Shen, Trushant K. Patel, Steven A. E. Miller
Summary: This study introduces a time-domain BBSAN model based on the vector Green's function solution, utilizing LES databases and Proper orthogonal decomposition to analyze shock-associated noise in off-design supersonic jets. By analyzing the predominant POD modes and noise source contour plots, the key features of BBSAN are revealed.
JOURNAL OF SOUND AND VIBRATION
(2021)
Article
Mathematics, Applied
Y. Zhang, M. Vanierschot
Summary: A three-dimensional incompressible annular jet was simulated using the large eddy simulation (LES) method at a Reynolds number Re = 8 500. The study focused on the flow dynamics of the wake flow, with particular attention to the proper orthogonal decomposition (POD) analysis of the velocity fluctuation vectors. The results showed that the first four eigenmodes captured significant turbulent kinetic energy, impacting the wake dynamics, with modes 1 and 2 related to a radial shift of the stagnation point, and modes 3 and 4 involving stretching or squeezing effects in the radial direction of the recirculation region.
APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION
(2021)
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
Computer Science, Interdisciplinary Applications
Michel Onori, Nicholas J. Hills
Summary: This paper presents a Reduced Order Modelling (ROM) approach for turbulent flow in a rotor-stator cavity commonly found in aircraft engine secondary air systems. The method uses Proper Orthogonal Decomposition (POD) with data from Large Eddy Simulations (LES) to predict turbulence phenomena accurately, introducing two novel techniques in the process.
COMPUTERS & FLUIDS
(2021)
Article
Construction & Building Technology
Yixun Liu, Chun-Ho Liu, Guy P. Brasseur, Christopher Y. H. Chao
Summary: The study implemented Proper orthogonal decomposition (POD) to analyze turbulence structures in the atmospheric surface layer (ASL) over real urban morphology, revealing potential impacts on urban wind risks and air quality. The results demonstrate the high capability of POD in reducing data dimensions and extracting flow characteristics, providing new insights for urban planning and air quality improvement.
SUSTAINABLE CITIES AND SOCIETY
(2023)
Article
Engineering, Marine
Shaoqiong Yang, Xuan Wang, Hao Wang, Nan Jiang
Summary: Turbulent drag on the hull surface is influenced by coherent structures in the boundary layer during ship navigation. This study used TRPIV to measure the flow field on the surface of a Japanese bulk carrier and analyzed the coherent structures using FTLE, POD, and quadrant analysis. The results indicate that the skin friction drag is significantly affected by the coherent structures and their burst events, and the turbulent energy and fluctuation velocity within the burst events contribute to the increase in skin friction drag. This study provides physical evidence for optimizing hull configurations, unmanned underwater vehicle design, and drag reduction strategies.
Article
Agronomy
I. M. Cely-Toro, L. Mortarini, C. Q. Dias Junior, U. Giostra, L. Buligon, G. A. Degrazia, D. Cava
Summary: This study investigates the influence of coherent vortices on turbulence structure above and below a dense plant canopy. Turbulence measurements collected at different levels within a coniferous forest on an Alpine Plateau were analyzed. The results show that the dominant time scale of momentum flux is mainly determined by the longitudinal wind velocity component under near-neutral conditions. In free convection and very stable conditions, the momentum transport is not influenced by coherent vortices generated at the canopy top.
AGRICULTURAL AND FOREST METEOROLOGY
(2023)
Article
Thermodynamics
Weimei Quan, Wenjing Sun, Jingzhou Zhang, Xiaoming Tan
Summary: Numerical investigations using large-eddy simulation were conducted to study the flow characteristics of pulsed jets in a crossflow. The evolution of flow mechanism and coherent structures were analyzed, showing that pulsed jets in a crossflow can form large-scale shear layer vortices and enhance turbulence pulsation, promoting mixing between jets and the crossflow.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Engineering, Mechanical
Wei Zhou, Y. F. Xu
Summary: This study investigates the use of Proper Orthogonal Modes (POMs) of guided wavefields for damage identification in beam-like structures. The continuous wavelet transform is employed to enhance local anomalies and suppress global trends, and an adaptive truncation technique is used to determine significant POMs for damage identification. Numerical and experimental investigations verify the accuracy and noise-robustness of the proposed method for identifying the location and extent of damage in beam-like structures.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Mechanics
Hirotaka Maeyama, Soshi Kawai
Summary: Near-wall turbulence structures and generation in the wall-modelled large-eddy simulation (WMLES) are investigated by comparing with direct numerical simulation (DNS). The near-wall statistical structures producing turbulence are found to exist even in the WMLES, although they are numerically elongated. The near-wall turbulence structures in the WMLES are suggested to be coherent structures with alternating low- and high-speed fluids in the spanwise direction.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Geochemistry & Geophysics
Jiangheng He, Zezong Chen, Chen Zhao, Xi Chen, Yunyu Wei, Chunyang Zhang
Summary: A novel method for wave parameter inversion based on spectral proper orthogonal decomposition (SPOD) is proposed in this study. The method processes the spatial-temporal series of wave orbital velocities using SPOD, removes nonwave contributions, and obtains wave parameters in good agreement with buoy measurements.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Engineering, Civil
Johannes Schobesberger, Dominik Worf, Petr Lichtneger, Sencer Yuecesan, Christoph Hauer, Helmut Habersack, Christine Sindelar
Summary: This study experimentally investigates entrainment events of a single sediment particle on a smooth bed in open channel flow. Tomographic particle tracking velocimetry system and shake the box algorithm were used to determine flow velocities, while proper orthogonal decomposition method was applied to identify motions carrying the most turbulent kinetic energy.
JOURNAL OF HYDRAULIC RESEARCH
(2022)
Article
Mechanics
Milad Samie, Vlad Aparece-Scutariu, Philippe Lavoie, Dong-hyuk Shin, Andrew Pollard
Summary: This study uses direct numerical simulation to investigate three-dimensional vortical and very-large-scale coherent structures in a turbulent round jet at a Reynolds number of 7300. The results show the importance of horseshoe vortices in the jet and the existence of symmetric and asymmetric horseshoe vortices that affect the high and low momentum regions in the flow.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Jiajun He, Qingsong An, Jiangshan Jin, Shuai Feng, Kemu Zhang
Summary: In this study, a visualization experiment and proper orthogonal decomposition (POD) method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle. Large eddy simulation (LES) was performed to explore the causes of cavitation shedding, and the relationship between cavitation and vortices. The re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds.
JOURNAL OF THERMAL SCIENCE
(2023)
Article
Engineering, Ocean
Aristos Christou, Zhihua Xie, Thorsten Stoesser, Pablo Ouro
Summary: In this study, the Hydro3D in-house large-eddy simulation code was refined to investigate wave structure interaction. The code accurately simulated solitary waves generation and propagation in a numerical wave tank, as well as wave interaction with both infinitely wide and finite square plates. Three-dimensional effects, such as span-wise flow and unique flow structures near the plate, were identified, along with variations in hydrodynamic forces and free-surface elevations when the plate is fixed at different angles of attack.
APPLIED OCEAN RESEARCH
(2021)
Article
Engineering, Civil
V Sriram, Shagun Agarwal, Shiqiang Yan, Zhihua Xie, Shaswat Saincher, Torsten Schlurmann, Qingwei Ma, Thorsten Stoesser, Yuan Zhuang, Bo Han, Weiwen Zhao, Xiaotong Yang, Z. Li, Decheng Wan, Yi Zhang, Bin Teng, Dezhi Ning, Ningbo Zhang, Xing Zheng, Guochun Xu, Jiaye Gong, Yunbo Li, Kangping Liao, Wenyan Duan, Ronggui Hann, Windiman Asnim, Zana Sulaiman, Zhongbing Zhou, Jianmin Qin, Yucheng Li, Zhiwei Song, Xiaofan Lou, Lin Lu, Changfu Yuan, Yuxiang Ma, Congfang Ai, Guohai Dong, Hanbing Sun, Qiang Wang, Zhi-Tao Zhai, Yan-Lin Shao, Zaibin Lin, Ling Qian, Wei Bai, Zhihua Ma, Pablo Higuera, Eugeny Buldakov, Dimitris Stagonas, Santiago Martelo Lopez, Aristos Christou, Pengzhi Lin, Yanyan Li, Jinshu Lu, Sa Young Hong, Yoon-Jin Ha, Kyong-Hwan Kim, Seok-Kyu Cho, Dong-Min Park, Wojciech Laskowski, Claes Eskilsson, Mario Ricchiuto, Allan P. Engsig-Karup, Lin Cheng, Jinhai Zheng, Hanbin Gu, Guangnian Li
Summary: This paper presents a comparative study on the interaction between focused waves and a fixed cylinder, using 20 numerical solvers developed by various universities. The qualitative and quantitative comparisons based on wave probe and pressure probe time histories and spectral components show differences among different solvers. The relative error analysis indicates variations in performance among the solvers, providing insights for industrial applications.
INTERNATIONAL JOURNAL OF OFFSHORE AND POLAR ENGINEERING
(2021)
Article
Thermodynamics
Arthur Hajaali, Thorsten Stoesser
Summary: The mean and instantaneous flow separation of two different three-dimensional asymmetric diffusers were analyzed using large-eddy simulations, showing good agreement with experimental data. The study further quantifies flow separation behavior and unsteadiness, revealing the volume portion in which the instantaneous reversal flow evolves. Analysis of power density spectra of time series indicates the periodicity of the growth and reduction phases of flow separation within the diffusers.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Engineering, Marine
Xingsen Guo, Tingkai Nian, Thorsten Stoesser
Summary: This paper investigates the impact forces induced by submarine landslides on a golfball-type dimpled pipeline surface using a computational fluid dynamics approach. The study finds that the golfball-type dimpled pipelines experience reduced drag forces and suppress lift force variations. A methodology for predicting the drag reduction and necessary conditions for lift force periodic vibrations are provided. Additionally, the paper reveals the full life cycle of vortices shed from the pipeline and the hydrodynamics during landslides impact on pipelines.
Article
Engineering, Marine
Xingsen Guo, Thorsten Stoesser, Tingkai Nian, Yonggang Jia, Xiaolei Liu
Summary: This paper investigates the influence of pipeline surface roughness on the interaction between submarine landslides and pipelines. The study establishes a methodology to estimate peak impact forces, providing a basis for risk assessment of submarine pipelines.
Article
Computer Science, Interdisciplinary Applications
Zhihua Xie, Pengzhi Lin, Thorsten Stoesser
Summary: A conservative and consistent three-dimensional Cartesian cut-cell method is proposed to reduce spurious pressure oscillations in moving body simulations. The method improves the moving body algorithm and enforces strict conservation of mass and momentum through pressure-velocity coupling. A consistent mass and momentum flux computation is employed, and an implicit time integration scheme is used to prevent numerical instability.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Mechanics
Yan Liu, T. Stoesser, H. Fang
Summary: This study investigates the effect of secondary currents on friction factor, statistics, and large-scale turbulent motion in partially filled pipes using large-eddy simulations. The results show that secondary currents originate from the corner between the free surface and the pipe walls, and their presence reduces the friction factor and the strength of near-wall structures. Therefore, partially filled pipe flows have lower drag and turbulent energy compared to fully filled pipe flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Civil
Congfang Ai, Yuxiang Ma, Changfu Yuan, Zhihua Xie, Guohai Dong, Thorsten Stoesser
Summary: This paper presents a simulation study of a solitary wave propagating over a submerged horizontal plate using a non-hydrostatic model and a high-resolution advection scheme. The results show that the length of the plate has a significant influence on the characteristics of vortex shedding and evolution, with longer plates resulting in more pronounced vortex structures.
JOURNAL OF HYDRAULIC RESEARCH
(2022)
Article
Engineering, Marine
Congfang Ai, Yuxiang Ma, Changfu Yuan, Zhihua Xie, Guohai Dong, Thorsten Stoesser
Summary: This paper presents a three-dimensional non-hydrostatic model for predicting the interaction between nonlinear waves and fixed floating structures. A new numerical algorithm is proposed to handle floating structures, and the model is validated by comparing its results with experimental data and other models.
Article
Mechanics
Yan Liu, Thorsten Stoesser, Hongwei Fang
Summary: This study investigates the response of turbulent flow and water surface fluctuations in partially filled pipes through large eddy simulations. The results show that as the water depth increases, the strength of the main secondary flow and the magnitude of water surface fluctuations also increase. Pre-multiplied spectra provide further evidence of the origin of the surface waves. Analysis of the wavenumber-frequency spectra reveals different types of surface waves.
Article
Environmental Sciences
Chenwei Zhao, Pablo Ouro, Thorsten Stoesser, Subhasish Dey, Hongwei Fang
Summary: Numerical simulations were conducted to explore the effects of natural bed roughness on bedload transport. The results show that as bed roughness increases, there is a shift in the velocity profiles, an increase in Reynolds stresses, and the fragmentation of coherent structures. The resting time of saltating particles increases while their saltation length, velocity, and angular velocity decrease.
WATER RESOURCES RESEARCH
(2022)
Article
Engineering, Civil
Filipa Adzic, Thorsten Stoesser, Yan Liu, Zhihua Xie
Summary: Large-eddy simulations were performed to study the characteristics of supercritical flow in a straight-wall, open-channel contraction. The results revealed that secondary currents in the contraction redistributed momentum, resulting in local up-and down-flows, and the energy loss was mainly caused by pressure drag.
JOURNAL OF HYDRAULIC RESEARCH
(2022)
Article
Engineering, Ocean
Xingsen Guo, Thorsten Stoesser, Cheng Zhang, Cuiwei Fu, Tingkai Nian
Summary: This study investigates the interaction between submarine landslides, ambient water, and pipelines using computational fluid dynamics (CFD) modeling and physical flume experiments. The effects of different boundary conditions on the impact forces on pipelines are explored, and the mechanism behind these force changes is explained through the analysis of velocity field, pressure field, and streamlines. A method for determining boundary conditions is proposed, providing a basis for optimizing CFD modeling in submarine landslide-pipeline interactions.
APPLIED OCEAN RESEARCH
(2022)
Article
Computer Science, Interdisciplinary Applications
Xingsen Guo, Thorsten Stoesser, Defeng Zheng, Qianyu Luo, Xiaolei Liu, Tingkai Nian
Summary: In this study, the method of computational fluid dynamics (CFD) was used to simulate a fluidized submarine landslide with shear thinning non-Newtonian fluids under different contact conditions. The accuracy of the CFD method was validated and various experiments were systematically performed. The stress state and causes of the submarine landslide mass during its movement in ambient water were revealed, and the submarine landslide-seabed contact relation was identified as a decisive influencing factor. Furthermore, a methodology based on energy conservation was presented to predict the run-out distance of the submarine landslide mass, and equations to quantify the process were established and validated by numerical results. This provides a significant basis for the prediction of marine engineering geological and hydrodynamic hazards related to submarine landslides.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Physics, Fluids & Plasmas
Razieh Jalalabadi, Thorsten Stoesser
Summary: This study examines the Reynolds and dispersive shear stresses in turbulent flow over spanwise-aligned square bars in an open channel flow. The analysis of large-eddy simulation results for two different bar spacings reveals that the contribution of Reynolds shear stress to the momentum loss is greater than that of the dispersive shear stress. However, by increasing the bars spacing, the contribution of the dispersive shear stress increases while the Reynolds shear stress contribution decreases. The study also investigates the dynamics of the flow and finds that there is a momentum source below the crest of the bars and a momentum sink above them, leading to acceleration or deceleration of flow. Furthermore, the quantification of the three components of total kinetic energy shows that the largest contribution is from the mean flow, and by increasing the bar spacing, the contributions of turbulent and wake kinetic energy increase while the kinetic energy of the mean flow decreases.
