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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 university of Science and Technology,Shanghai 2.02.7,{2. 2.Research center for Fluid Dynamics,PLA university of Science and Technology,nanjing 2.1101,{2. 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 university of Technology, Dalian 11602.,{2. 2.Research center for Fluid Dynamics, School of Science, PLA university of Science and Technology, nanjing 2.1101,{2. 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

A relative local variational principle for topological pressure

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Science china Mathematics 2010年第6期53卷 1491-1506页

作者： MA XianFeng1,CHEN ErCai2.3,& ZHANG AiHua2.4 1Department of Mathematics,East china university of Science and Technology,Shanghai 2.02.7,{2. 2.chool of Mathematics and Computer Science,nanjing Normal university,nanjing 2.0097,{2. 3center of Nonlinear Science,nanjing university,nanjing 2.0093,{2. 4College of Mathematics and Physics,nanjing university of Posts and Telecommunications,nanjing 2.0046,{2. 1. Department of Mathematics East China University of Science and Technology Shanghai 200237 China2. School of Mathematics and Computer Science Nanjing Normal University Nanjing 210097 China3. Center of Nonlinear Science Nanjing University Nanjing 210093 China4. College of Mathematics and Physics Nanjing University of Posts and Telecommunications Nanjing 210046 China

We define the relative local topological pressure for any given factor map and open cover,and prove the relative local variational principle of this *** precisely,for a given factor map π:(X,T)→(Y,S) between two topological dynamical systems,an open cover U of X,a continuous,real-valued function f on X and an S-invariant measure ν on Y,we show that the corresponding relative local pressure P(T,f,U,y) satisfies sup μ∈M(X,T){ hμ(T,U|Y)+∫X f(x)dμ(x) :πμ=ν}=∫Y P(T,f,U,y)dν(y),where M(X,T) denotes the family of all T-invariant measures on ***,the supremum can be attained by a T-invariant measure.

关键词： pressure conditional entropy relative local variational principle

Estimation of suspended sediment concentration based on bio-optical mechanism and HJ-1 image in Chaohu Lake

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Science china Earth Sciences 2010年第S1期53卷 58-66页

作者： WANG Qiao1,2.JIN Xin2.LI YunMei2.WU ChuanQing1,Lü Heng2.WANG YanFei2.ZHANG Hong2.YIN Bin2.& ZHU Li1 1Satellite Environment center,Ministry of Environmental Protection,Beijing 10002.,china 2.ey Laboratory of Virtual Geographic Environment of Education Ministry,{2. Normal university,{2. 2.0046,china 1. Satellite Environment center Ministry of Environmental Protection Beijing 100029 China2. Key Laboratory of Virtual Geographic Environment of Education Ministry Nanjing Normal University Nanjing 210046 China

Synchronization experiment was conducted in June,2.09 to get Inherent Optical Properties(IOP) of water component in Chaohu *** bio-optical mechanism was studied combined with multispectral data of Environmental Satellite 1(CCD),and then inversion models of total suspended matter(TSM),inorganic suspended matter(ISM) and organic suspended matter(OSM) concentration were *** data indicated that:the absorption ratio of suspended particulate matter and CDOM to total were almost no change from band 1 to band 2.with about 85% and 9%,*** ratio of pure water to total increased from 0.4% to 5.6%.Water reflectance in these two bands were influenced by absorption of three kinds of components:algae particles absorption surpassed non-algal particles in band 3,and so played an important role in total absorption with about 35.7%;the proportion of pure water absorption and particles matter backscattering both were 99% in band 4,so these two components decided the main inherent optical properties in band *** models of TSM and ISM concentration inversion based on band combination(band 3 + band 4)/(band 1 + band 2. were built,while OSM concentration was estimated by band 4/(band 1 + band 2. *** by image data,RE of TSM concentration between modeled and measured was 33.4%,and RMSE was 18.68 mg/*** of ISM and OSM concentration were 39.9% and 35.2. *** inversion was more accurate when satellite-ground data were just in the same *** this situation,RE of ISM concentration dropped to 2..4%,and that of TSM and OSM reduced to 2..5% and 2..8% as well.

关键词： HJ-1 Satellite bio-optical property Chaohu Lake suspended matter

Probing proton halo of the exotic nucleus ^(2.)S by elastic electron scattering

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Science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 42-51页

作者： WANG Zaijun1 & REN Zhongzhou1’2.1. Department of Physics, nanjing university, nanjing 2.0008,{2. 2. center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator at Lanzhou, Lanzhou 730000,{2. Correspondence should be addressed to Ren Zhongzhou (email: zren@*** zren99@***) Received June 16, 2.03 1. Department of Physics Nanjing University 210008 Nanjing China 2. center of Theoretical Nuclear Physics National Laboratory of Heavy-Ion Accelerator at Lanzhou 730000 Lanzhou China

Elastic electron scattering on the exotic light nucleus 2.S is investigated in the plane wave Born approximation. The variation of the squared form factors of 2.S with momentum transfer is compared with that of 32.. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in 2.S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.

关键词： elastic electron scattering, cross section, form factor, proton-halo nucleus.

Detection of subcritical crack propagation for concrete dams

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Science china(Technological Sciences) 2009年第12期52卷 3654-3660页

作者： BAO TengFei1 ,2.YU Hong 1,2.1College of Water Conservancy&Hydropower Engineering,Hohai university,nanjing 2.0098,{2. 2.ational Engineering Research center of Water Resources Efficient Utilization and Engineering Safety,nanjing 2.0098,{2. College of Water Conservancy & Hydropower Engineering Hohai University Nanjing 210098 China National Engineering Research center of Water Resources Efficient Utilization and Engineering Safety Nanjing 210098 China

Subcritical propagation of cracks is a warning sign of *** such propagation is detected at an early stage,timely maintenance measures can be taken to prevent the failure of *** detect the subcritical propagation of a crack,the crack needs to be monitored continuously in a long term, which is not realistic under certain ***,cracks in concrete dams can be monitored continuously by dam monitoring to offer possible detection for subcritical *** this paper, with measured crack openings from dam monitoring,a state equation for characterizing crack development is established based on the grey system *** relation between the stability of the equation and the subcritical crack propagation is investigated,then a criterion is proposed for detecting subcritical *** example demonstrates the validity of the criterion and its potential for practical application.

关键词： crack subcritical propagation criterion concrete

Back analysis of mechanical parameters of roller compacted concrete dam

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Science china(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1,2.3,LI Bo 1,XU GuangLei 4 &YU Hong 1,2.3 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai university,nanjing 2.0098,{2. 2.ollege of Water Conservancy Hydropower,Hohai university,nanjing 2.0098,{2. 3National Engineering Research center of Water Resources Engineering Safety,Efficient Utilization and nanjing 2.0098,{2. 4 nanjing Hydraulic Research Institute,nanjing 2.002.,{2. 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China2. College of Water Conservancy Hydropower Hohai University Nanjing 210098 China3. National Engineering Research Center of Water Resources Engineering Safety Efficient Utilization and Nanjing Nanjing 210098 China4. Nanjing Hydraulic Research Institute Nanjing 210029 China

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

Multivariate analysis in dam monitoring data with PCA

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Science china(Technological Sciences) 2010年第4期53卷 1088-1097页

作者： YU Hong1,2.WU ZhongRu1,2.BAO TengFei1,2.& ZHANG Lan1,2.1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai university,nanjing 2.0098,{2. 2.National Engineering Research center of Water Resources Efficient Utilization and Engineering Safety,Hohai university,nanjing 2.0098,{2. 1. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China2. National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China

Given the limitation of traditional univariate analysis method in processing the multicollinearity of dam monitoring data,this paper reconstructs the multivariate response variables by introducing principal component analysis(PCA) method,explores the ways of determining principal components(PCs),and extracts a few PCs that have major influence on data *** steady observation series,a control field for the whole observation values has been established based upon PCA;for unsteady observation series that have significant tendency,a control field for the future observation values has been constructed according to PC statistical predication *** methods have already been applied to an actual project and the results showed that data interpretation method with PCA can not only realize data reduction,lower data redundancy,and reduce noise and false alarm rate,but also be effective to data analysis,having a broad application prospect.

关键词： dam safety monitoring multivariate response variables principal component analysis data reduction

Research on stability of the accumulated rock-soil body of reservoir bank under rainfall condition

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Science china(Technological Sciences) 2009年第9期52卷 2528-2535页

作者： GU ChongShi1,2.WU HaiZhen1,2.& SU HuaiZhi1,2.1 College of Water Resources and Hydropower Engineering,Hohai university,nanjing 2.0098,{2. 2.National Engineering Research center of Water Resources Efficient Utilization and Engineering Safety,Hohai university,nanjing 2.0098,{2. 3 Jiangxi Water Conservancy Research Institute,Nanchang 33002.,{2. 1. College of Water Resources and Hydropower Engineering Hohai University Nanjing 210098 China 2. National Engineering Research center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China 3. Jiangxi Water Conservancy Research Institute Nanchang 330029 China

The shear strength parameters property of rock-soil aggregates in embankment slope of reservoir,that is,the relationship between cohesion and gravel content,between friction angle and gravel content,and the relationship between cohesion and water content,between friction angle and water content,is studied based on the direct shear test results,the shear strength change law of the rock-soil aggregates is given,and the unsaturated shear strength formulation of rock-soil aggregates that could consider suction and saturation degree influence is put forward in this paper,through which the sliding or failure physical mechanism of this type of slope under the condition of rainfall infiltration is studied. Also the 3D unsteady saturated-unsaturated seepage field and its FEM resolving mode are established based on the analysis of the slope rainfall infiltration process. Case study with this method indicates that the minimum safety factor of the accumulated rock-soil aggregates dose not arrive at the moment of rainfall cessation,but appears several hours after the rainfall cessation,this phenomenon is in accordance with the practical slope engineering's failure process and could explain appropriately the slope failure caused by rainfall infiltration. Research results in this paper have an important reference value for the research on stability of the accumulated rock-soil aggregates in embankment slope of reservoir,and can enrich the stability analysis method and relevant theory of reservoir embankment slope.

关键词： reservoir bank slope rock-soil aggregates rainfall infiltration saturated/unsaturated seepage