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science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： wang liang1 & wu chuijie2,3 1 school of science,pla univ.rsity of science and technology,nanjing 211101,china 2 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian univ.rsity of technology,Dalian 116024,china 3 school of Aeronautics and Astronautics,Dalian univ.rsity of technology,Dalian 116024,china 1. school of science PLA University of Science and Technology Nanjing 211101 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at Re=40 and Re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3) the self-propelled fish-like swimming at Re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

Large-Eddy Simulations of turbulent flows with lattice Boltzmann dynamics and dynamical system sub-grid models

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science china(Technological sciences) 2009年第3期52卷 670-679页

作者： GUAN Hui1 & wu chuijie2 1 Research Center for Fluid Dynamics, pla univ.rsity of science and technology, nanjing 211101, china 2 school of Aeronautics and Astronautics, Dalian univ.rsity of technology, Dalian 116024, china Research Center for Fluid Dynamics PLA University of Science and Technology Nanjing 211101 China school of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

In this paper, two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM), i.e., the dynamics SGS model and the dynamical system SGS model, and applied to numerically solving three-dimensional high Re turbulent cavity flows. Results are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same cases. It is shown that the method with LBM dynamics SGS model has advantages of fast computation speed, suitable to simulate high Re turbulent flows. In addition, it can capture detailed fine structures of turbulent flow fields. The method with LBM dynamical system SGS model dose not contain any adjustable parameters, and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field, such as the backscatter of energy transportation between large and small scales. A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.

关键词： Large-Eddy Simulation Lattice Boltzmann Method dynamics sub-grid scale model dynamical system sub-grid scale model parallel computation

Large-eddy simulations and vortex structures of turbulent jets in crossflow

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： GUAN Hui1,2 & wu chuijie2 1 school of Mechanical and Power Engineering,East china univ.rsity of science and technology,Shanghai 200237,china 2 Research Center for Fluid Dynamics,pla univ.rsity of science and technology,nanjing 211101,china 1. school of Mechanical and Power Engineering East China University of Science and Technology Shanghai 200237 China 2. Research Center for Fluid Dynamics PLA University of Science and Technology Nanjing 211101 China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

A method of constructing a database-free optimal dynamical system and a global optimal dynamical system

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science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 905-915页

作者： wu chuijie1? & wang liang2 1 State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian univ.rsity of technology, Dalian 116024, china 2 Research Center for Fluid Dynamics, school of science, pla univ.rsity of science and technology, nanjing 211101, china 1. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China 2. Research Center for Fluid Dynamics School of Science PLA University of Science and Technology Nanjing 211101 China

In this paper, to overcome the drawbacks of POT which minimize the reminder, not only the optimal functional with minimal residual is put forward, but also the method of global optimization is used. Under the condition of large reminder, the optimal bases can also be obtained through the method of POTres without the approaching of initial conditions. In addition, compared with local optimization, the advantage of global optimization is remarkable. On the one hand, we can expect that the dynamical system based on the global optimal bases will include more information than the ones based on the local optimal bases, since the global optimal bases are much more precise than the local optimal bases. On the other hand, from the point of view of error, the global optimal bases are independent of the choice of the object functional and the initial bases.

关键词： dynamical system residual global optimization

Large-eddy simulation of formation of three-dimensional aeolian sand ripples in a turbulent field

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science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 945-960页

作者： wu chuijie1,wang Ming2 & wang liang3 1 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian univ.rsity of technology,Dalian 116024,china 2 Yellow River Institute of Hydraulic Research,Zhengzhou 450003,china 3 Research Center for Fluid Dynamics,science school,pla univ.rsity of science and technology,nanjing 211101,china State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China Yellow River Institute of Hydraulic Research Zhengzhou 450003 China Research Center for Fluid Dynamics Science School PLA University of Science and Technology Nanjing 211101 China

With the method of large-eddy simulation,the equation of spherule motion and the method of immersed boundary condition,numerical simulations of three-dimen-sional turbulent aeolian motion and the formation of sand ripples under three-di-mensional turbulent wind and the mutual actions of saltation and creeping motion were carried out. The resulting sand ripples have the form that is flat on the upwind side and steep on the leeward,which is identical to the sand ripples in nature. We also realized the self-restoration process of three-dimensional sand ripples,which shows the correctness of the method of numerical simulation and the models of saltation and creeping. Finally,We analyzed the influence of sand ripples on the three-dimensional turbulent wind field,and found that due to the appearance and development of sand ripples,in the normal direction of ground there exists stronger energy exchange,and moreover,there is close correspondence between the forms of sand ripples and the vorticity close to the ground surface.

关键词： large-eddy simulation equation of spherule motion sand ripples saltation creep

Screening of transition metal oxides for electrocatalytic nitrate reduction to ammonia at large currents

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Nano Research 2024年第5期17卷 3902-3910页

作者： Qiongfei wu Weijie Zhu Dongxu Ma Chao liang Zhoucheng wang Hanfeng liang State Key Laboratory of Physical Chemistry of Solid Surfaces Tan Kah Kee Innovation LaboratoryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China College of Chemical Engineering Tianjin UniversityTianjin 300072China

Electrochemical nitrate reduction reaction(NO_(3)RR)towards ammonia,as an emerging and appealing technology alternative to the energy-intensive Haber-Bosch process and inefficient nitrogen reduction reaction,has recently aroused wide concern and ***,the current research of the NO_(3)RR towards ammonia lacks the overall performance comparison of various *** this,we here make a comparison of 12 common transition metal oxide catalysts for the NO_(3)RR under a high cathodic current density of 0.25 A·cm^(-2),wherein Co_(3)O_(4) catalyst displays the highest ammonia Faradaic efficiency(85.15%)and moderate activity(ca.-0.25 V *** hydrogen electrode).Other external factors,such as nitrate concentrations in the electrolyte and applied potential ranges,have also been specifically investigated for the NO_(3)RR.

关键词： nitrate reduction reaction ammonia production transition metal oxides Co_(3)O_(4)

Design of Support Effect in the Catalytic Application of Ligand-Protect Gold Clusters

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Chinese Journal of Chemistry 2024年第1期42卷 73-86页

作者： Shuohao Li Shenguang Fu Yuqing Gong Nuojie wu Lei wang liang wang school of Safety Engineering China University of Mining and TechnologyXuzhouJiangsu 221116China schoolof Chemistry and Chemical Engineering Yangzhou UniversityYangzhouJiangsu 225009 Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization China University of Mining and Technology XuzhouJiangsu 221008China

Ligand-protected gold(Au_(n))clusters sometimes need the removal of organic ligands to expose more active sites and reduce steric hindrance in catalytic reactions,and large amount of organic and inorganic materials usually need to be employed as supports to anchor Aun clusters through different interaction ***,less comprehensive summaries have been provided about the crucial contribution of various supports to the catalytic performance of the supported Aun ***,this review firstly summarizes synthesis methods(e.g.,impregnation and encapsulation processes)for the supported Aun cluster catalysts,and then mainly points out specific contributions of support effect in a great diversity of catalytic reactions,as well as deep interaction ***,opportunities and challenging issues will be stated towards supported Aun clusters,in terms of improving catalytic performance and structural stability of Aun clusters inthedemand of catalysis.

关键词： Gold clusters Synthesis Support effect Catalytic performance Interaction

Modified electronic structure and enhanced hydroxyl adsorption make quaternary Pt-based nanosheets efficient anode electrocatalysts for formic acid-/alcohol-air fuel cells

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Journal of Energy Chemistry 2024年第5期92卷 142-150页

作者： Fengling Zhao Qiang Yuan Siyang Nie liang wu Xun wang State-Local Joint Laboratory for Comprehensive Utilization of Biomass Center for R&D of Fine ChemicalsCollege of Chemistry and Chemical EngineeringGuizhou UniversityGuiyang 550025GuizhouChina Key Lab of Organic Optoelectronics&Molecular Engineering Tsinghua UniversityBeijing 100084China school of Chemistry and Chemical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet ***,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel *** modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/*** in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct *** functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic *** synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.

关键词： Pt-based nanosheets Modifiedelectronic structure Enhanced hydroxyl adsorption Formicacidand alcohol oxidation Direct liquid fuel cells

Realizing the purification and grain refinement of Mg-Gd-Y alloy by one-step flux refining

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Journal of Materials science & technology 2024年第6期173卷 202-217页

作者： Xin Tong Guohua wu Ming Sun Qiman wang liang Zhang Wencai Liu National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China school of Materials and Chemistry University of Shanghai for Science and TechnologyShanghai 200093China

In the conventional melt preparation of magnesium rare-earth(Mg-RE)alloys,the repeated heating/cooling process involved in grain refinement and flux refining usually prolongs the preparation period and aggravates melt *** this work,the purification and grain refinement of Mg-9Gd-3Y(GW93)alloy was simultaneously realized by one-step refining at 740℃ by using a self-developed compound *** results show that,only after holding for 10 min,the inclusion content of the alloy is reduced by 81%to 0.29%,while the grain size is reduced by 84%to 119μm.A physical model depicting the interactions between compound flux and alloy melt was proposed based on thermodynamic calculation and microstructure *** grain refinement mechanism has been analyzed by considering the presence of Zr particle(Zr_(p))and Zr solute(Zr_(s)).In addition,the generated RECl_(3) was found to be readily absorbed by the flux,decreasing the surface tension and promoting the purification efficacy of the flux,which plays an important role in the promoted elongation of the as-cast Mg-9Gd-3Y-0.5Zr(GW93K)*** work presents a unique prospect in simplifying the melt preparation of Mg-RE alloy with a promoted quality.

关键词： Mg-Gd-Y-Zr alloy Purification Grain refinement Compound flux Settling behavior

Theoretical and experimental research on static stiffness,performance,and lift-off characteristics of multi-layer gas foil thrust bearings

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Friction 2024年第11期12卷 2458-2479页

作者： Yang HU Pengjing DING Fangling wu Xiaojing wang Bo liang Yonggang MENG school of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072China Aviation Key Laboratory of science and technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft SystemsNanjing 211106China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foil,as well as the Coulomb friction effect,are *** stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement,which verifies the accuracy of the *** contribution of each foil layer to the overall stiffness and the load-carrying mechanism are *** effects of the load,preload,and rotational speed on the static performance are investigated ***,start–stop tests are performed to achieve the lift-off speed,start-up torque,and shut-down torque under various operating conditions.

关键词： multi-layer gas foil thrust bearing(GFTB) load carrying mechanism static performance