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Gully erosion and expansion mechanisms in loess tablelands and the scientific basis of gully consolidation and tableland protection

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Science China Earth Sciences 2023年第4期66卷 821-839页

作者： Zhao JIN Jianbing PENG Jianqi ZHUANG Li FENG Aidi HUO Xingmin MU Wenlong WANG State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China CAS Center for Excellence in Quaternary Science and Global Change Xi’an 710061China School of Human Settlements and Civil Engineering Xi’an Jiaotong UniversityXi’an 712000China College of Water and Environment Chang’an UniversityXi’an 710054China Yellow River Research Center Hohai UniversityNanjing 210024China Institute of Soil and Water Conservation Northwest A&F UniversityYangling 712100China Institute of Global Environmental Change Xi’an Jiaotong UniversityXi’an 710049China

Gully erosion is serious in the tableland area of the Loess Plateau due to high-intensity human activities and extreme rainfall, which cause serious soil loss and an increasing tableland shrinkage rate. Severe gully erosion has exerted a notable negative impact on local agriculture, human life and socioeconomic development. In recent decades, progress has been made in soil and water conservation with the goal of reducing soil erosion and protecting loess tableland, but basic research on gully consolidation and tableland protection(GCTP) is lacking, especially regarding the mechanisms of gully erosion and expansion in loess tableland under the interactive impacts of hydrodynamics and human activities. In addition, there is a lack of a deep understanding of the underlying mechanisms of soil-water disasters and controlling factors of unreasonable GCTP projects.Currently, the problems of headcut erosion and tableland fragmentation remain serious. Based on this situation, the Dongzhi tableland, the largest tableland on the Loess Plateau, was adopted as an example, and we studied gully erosion and expansion mechanisms in the loess tableland and the scientific basis of GCTP projects. We obtained a series of novel findings, including the following:(1) vertical joints are widely developed in loess and impose a controlling effect on tableland edge erosion;(2) rapid urbanization and road network expansion intensify headcut erosion and are the main reasons for severe erosion and tableland shrinkage in the Dongzhi tableland;and(3) unreasonable drainage of surface runoff and a rise in the groundwater level are the key factors affecting GCTP project stability. Moreover, the mechanisms and modes of erosion disasters in the project driven by these two factors were explained. The systematic remediation idea of retention, storage, drainage and consolidation for the GCTP project was introduced, and the core is water control, which emphasizes the combination of soil and water conservation and geohazard prevention measures. As a syste

关键词： Human activities hydrodynamics Tableland shrinkage Gully consolidation and tableland protection Failure mechanism Remediation mode

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Oil droplet movement and micro-flow characteristics during interaction process between gas bubble and oil droplet in flotation

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Chinese Journal of Chemical Engineering 2022年第5期35卷 229-237页

作者： Shenglin Yan Yan Zhang Chong Peng Xiaoyong Yang Yuan Huang Zhishan Bai Xiao Xu State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process School of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China Sinopec Dalian Research Institute of Petroleum and Petrochemicals Dalian 116041China Institute of Environmental Pollution and Health School of Environmental and Chemical EngineeringShanghai UniversityShanghai 200444China

Flotation is an efficient pre-treatment technology for oily water.In this work,the interaction process between the moving oil droplet and the gas bubble was studied by high-speed camera and Bassset-Boussinesq-Oseen(BBO)theoretical model,and the experimental and simulation results of the oil droplet trajectory were compared.Moreover,the micro-particle image velocimetry system was utilized to observe the flow inside and outside of the moving oil droplet.The results show that the BBO model with the mobile bubble’s surface can reflect the velocity change trend of the oil droplet during the interaction process between the moving oil droplet and the gas bubble,but there are some significant differences between the experimental and simulation results.While the oil droplet is moving on the bubble’s surface,the velocity of the area near the contact point of oil droplet–gas bubble is less than that of the other areas inside the oil droplet.Meanwhile,the flow of water above the oil drop is more biased towards the gas bubble.

关键词： Flotation Oil droplet-gas bubble interaction Approach process hydrodynamics

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Multi-Parameter Influence Analysis of Interaction Between Internal Solitary Wave and Fixed Submerged Body

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China Ocean Engineering 2023年第6期37卷 934-947页

作者： LIU Shuang HE Guang-hua ZHANG Zhi-gang HU Chang-hong ZHANG Cheng WANG Zheng-ke XIE Hong-fei School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001China Shandong Institute of Shipbuilding Technology Weihai 264209China School of Ocean Engineering Harbin Institute of TechnologyWeihaiWeihai 264209China Research Institute for Applied Mechanics Kyushu UniversityFukuoka 816-0811Japan

To obtain the interaction characteristics between Internal solitary waves(ISWs)and submerged bodies,a three-dimensional numerical model for simulating ISWs was established in the present study based on the RANS equation.The velocity entrance method was adopted to generate the ISWs.First,the reliability of this numerical model was validated by comparing it with theoretical and literature results.Then,the influence of environmental and navigation parameters on interactions between ISWs and a fixed SUBOFF-submerged body was studied.According to research,the hydrodynamic performance of the submerged body has been significantly impacted by the ISWs when the body is nearing the central region of the wave.Besides,the pitching moment(y')will predominate when the body encounters the ISWs at a certain angle between 0°and 180°,and the lateral force is larger than the horizontal force.Additionally,the magnitude of the force acting on the body is mostly affected by the wave amplitude.The variation of the vertical force is the main way that ISWs affect the hydrodynamic performance of the bodies.The investigations and findings discussed above can serve as a guide to forecast how ISWs will interact with submerged bodies.

关键词： CFD internal solitary waves submerged body multi-parameters influence hydrodynamics

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Numerical micro-texture optimization for lubricated contacts-A critical discussion

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Friction 2022年第11期10卷 1772-1809页

作者： Max MARIAN Andreas ALMQVIST Andreas ROSENKRANZ Michel FILLON Department of Mechanical and Metallurgical Engineering Pontificia Universidad Católica de ChileSantiago 690411Chile Division of Machine Elements LuleåUniversity of TechnologyLuleåSE-97187Sweden Department of Chemical Engineering Biotechnology and MaterialsFCFMUniversity of ChileSantiago 8370456Chile Institut Pprime CNRSUniversity of PoitiersPoitiers Cedex TSA 4112386073France

Despite numerous experimental and theoretical studies reported in the literature,surface micro-texturing to control friction and wear in lubricated tribo-contacts is still in the trial-and-error phase.The tribological behaviour and advantageous micro-texture geometries and arrangements largely depend on the contact type and the operating conditions.Industrial scale implementation is hampered by the complexity of numerical approaches.This substantiates the urgent need to numerically design and optimize micro-textures for specific conditions.Since these aspects have not been covered by other review articles yet,we aim at summarizing the existing state-of–the art regarding optimization strategies for micro-textures applied in hydrodynamically and elastohydrodynamically lubricated contacts.Our analysis demonstrates the great potential of optimization strategies to further tailor micro-textures with the overall aim to reduce friction and wear,thus contributing toward an improved energy efficiency and sustainability.

关键词： micro-texturing hydrodynamics elastohydrodynamics tribo-simulation optimization

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Computational fluid dynamic simulation of gas-liquid flow in rotating packed bed:A review

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Chinese Journal of Chemical Engineering 2022年第1期35卷 85-108页

作者： Wen-Cong Chen Ya-Wei Fan Liang-Liang Zhang Bao-Chang Sun Yong Luo Hai-Kui Zou Guang-Wen Chu Jian-Feng Chen Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China StateKey Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

The rotating packed bed(RPB)has been widely used in gas-liquid flow systems as a process intensification device,exhibiting excellent mass transfer enhancement characteristics.However,the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods.In the past two decades,Computational fluid dynamics(CFD)has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design.This article covers the development of the CFD simulation of gasliquid flow in RPB.Firstly,the improvement of the simulation method in the aspect of mathematical models,geometric models,and solving methods is introduced.Secondly,new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed,including pressure drop,velocity distribution,flow pattern,and concentration distribution,etc.Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works.In addition,the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications.The defects of current research and future development directions are also discussed at last.

关键词： Rotating packed bed Computational fluid dynamics Simulation hydrodynamics Mass transfer

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Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

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Acta Geologica Sinica(English Edition) 2022年第1期96卷 1-25页

作者： CHI Guoxiang XU Deru XUE Chunji LI Zenghua Patrick LEDRU DENG Teng WANG Yumeng SONG Hao Department of Geology University of Regina3737 Wascana ParkwayReginaSK S4S 0A2Canada State Key Laboratory of Nuclear Resources and Environment School of Earth SciencesEast China University of TechnologyNanchang 330013China State Key Laboratory of Geological Processes and Mineral Resource School of Earth Sciences and ResourcesChina University of GeosciencesBeijing 100083China Universite Lorraine UMR 7359 GeoRessources54506 Vandœuvre les NancyFrance Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province Chengdu University of TechnologyChengdu 610059China

Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties.Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration.One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization.This paper reviews the principles of hydrodynamics of mineralization,especially the nature of relationships between mineralization and structures,and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems.Three categories of mineralization systems were examined,i.e.,magmatic-hydrothermal systems,structurally controlled hydrothermal systems with uncertain fluid sources,and hydrothermal systems associated with sedimentary basins.The implications for deep mineral exploration,including potentials for new mineral resources at depth,favorable locations for mineralization,as well as uncertainties,are discussed.

关键词： hydrodynamics structural control of mineralization mineral systems shallow and deep mineralization deep mineral exploration

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The Nonlinear Field Equation of the Three-point Correlation Function of Galaxies:to the Second Order of Density Perturbation

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Research in Astronomy and Astrophysics 2022年第4期22卷 160-168页

作者： Shu-Guang Wu Yang Zhang Department of Astronomy Key Laboratory for Researches in Galaxies and CosmologyUniversity of Science and Technology of ChinaHefei 230026China

Based on the field theory of density fiuctuation under Newtonian gravity,we obtain analytically the nonlinear equation of 3-pt correlation functionζof galaxies in a homogeneous,isotropic,static universe.The density fiuctuation has been kept up to second order.By the Fry-Peebles ansatz and the Groth-Peebles ansatz,the equation ofζbecomes closed and differs from the Gaussian approximate equation.Using the boundary condition inferred from the data of SDSS,we obtain the solutionζ(r,u,θ)at fixed u=2,which exhibits a shallow U-shape along the angleθand,nevertheless,decreases monotonously along the radial r.We show its difference with the Gaussian solution.As a direct criterion of non-Gaussianity,the reduced Q(r,u,θ)deviates from the Gaussianity plane Q=1,exhibits a deeper U-shape alongθand varies weakly along r,agreeing with the observed data.

关键词： gravitation hydrodynamics cosmology:large-scale structure of universe

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Complexity of charged anisotropic spherically symmetric fluids in f(G)gravity

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Communications in Theoretical Physics 2023年第3期75卷 91-104页

作者： Z Yousaf M Z Bhatti M M M Nasir Department of Mathematics University of the PunjabQuaid-i-Azam CampusLahore-54590Pakistan

The previous ideology of complexity factor for the dynamical spheres[Herrera et al 2018,Phys.Rev.D,98,104059]is extended for the influence of charge.A dynamical spherically symmetric non-dissipative and dissipative self-gravitating structure is examined in the presence of Maxwell f(G)gravity to examine the complexity factor.The pattern of evolution is studied with the minimal complexity constraint.The complexity factor remains the same for the structure of fluid distribution,while we examine homologous constraints for the most basic evolution pattern.We calculate the structure scalars which play an important role in order to understand the fundamental properties of the system.The fluid is geodesic as well as shearing for the dissipative case and there is a large number of solutions.In the non-dissipative fluid distribution,a shear-free,homogeneous and isotropic,geodesic fluid correlates with the evolving homologous and vanishing complexity condition.The implication of the condition of vanishing complexity factor and stability are discussed at the end.

关键词： gravitation anisotropy complexity hydrodynamics

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Effect of gravel content on the detachment of colluvial deposits in Benggang

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Journal of Mountain Science 2022年第11期19卷 3088-3104页

作者： ZHANG Li-ting SHUAI Fang CHEN Li-bo HUANG Yan-he LIN Jin-shi ZHANG Yue GE Hong-li JIANG Fang-shi Jinshan Soil and Water Conservation Research Center Fujian Agriculture and Forestry UniversityFuzhou 350002China

Accurately calculating detachment capacity is the most fundamental issue when establishing a soil erosion process model.Colluvial deposits of Benggang are typical soil-gravel mixtures,whereas the understanding of the soil detachment of colluvial deposits is limited.This work investigated the effects of the gravel contents on the soil detachment capacity of colluvial deposits and its hydrodynamic mechanism.The colluvial sample was collected in Anxi County,Fujian Province,Southeast China,and a small-sample scouring test was used.The slope steepness ranged from 18%to 84%,unit discharge ranged from 0.56×10^(-3)to 2.22×10^(-3)m^(2)s^(-1),and gravel content ranged from 0%to 70%.The results indicated that the gravel content is the primary factor that influences the detachment capacity,followed by the discharge and then the slope.The detachment capacity trend with the gravel content varied over different slopes and discharges.Stream power represents the best hydrodynamic parameter for modelling the detachment capacity of colluvial deposits and can be used to establish a fitting equation for the colluvium together with the mean weight diameter(MWD)(Nash-Sutcliffe efficiency(NSE)=0.96).As the gravel content increased,the soil erodibility parameters increased several folds,in some cases more than 10 folds,mainly because the soil shear strength decreased gradually.Meanwhile,as the gravel content increased,the gravel specific surface area increased,the obstruction of gravel to runoff increased,and the energy needed for runoff to overcome gravel obstruction increased,leading to 2-3 folds higher critical shear stress of runoff for soilgravel mixtures compared with pure soil.In summary,gravel can influence the detachment capacity by changing the soil properties,and the gravel content also affects the relationship between soil detachment capacity and the hydrodynamic parameters.These findings deepen the understanding of the influence of gravel on soil erosion and provide a basis for establishing a soil erosion process model in co

关键词： Hydraulic erosion hydrodynamics Gravel content Soil detachment Erosion resistance Benggang

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Numerical investigation of mass transfer behavior of a gas-liquid two‐phase Taylor flow in a microchannel by a volume‐of‐fluid multiphase flow system

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International Journal of Mechanical System Dynamics 2022年第3期2卷 253-264页

作者： Qiuwen Zhong Zhen Jiao Wenhui Nie Yan Li Ning Gu Jiangsu Key Laboratory for Biomaterials and Devices Southeast UniversityNanjingChina Joint Research Institute of Southeast University and Monash University SuzhouChina School of Chemistry and Chemical Engineering Southeast UniversityNanjingChina School of Biological Science and Medical Engineering Southeast UniversityNanjingChina

The microchannel reactor is the most commonly used microreaction technology,an innovative reaction system developed in recent years.This study investigates the mass transfer behavior of a gas-liquid two‐phase Taylor flow in a microchannel by coupling the volume‐of‐fluid model and the species transport model.The concentration distribution and the volumetric mass transfer coefficient of the gas solute are determined and discussed in detail.The simulation results reveal that the double‐circulation flow influences the concentration distribution in the liquid slug.The highest value is observed at the bubble's surface and decreases rapidly along the vertical direction of the bubble.The increase of bubble velocity leads to a more apparent decreasing trend.The gas-liquid interface renewal rate of the bubble is accelerated with increasing bubble velocity,resulting in an increase in the average mass transfer rate in all regions of the bubble surface with an increase in bubble velocity.The results also indicate that the liquid film area contributes the most to the mass transfer behavior due to the most significant proportion and average mass transfer rate of the liquid film among the bubble.

关键词： Taylor flow microchannel hydrodynamics mass transfer behavior CFD simulation gas-liquid interface

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