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HYDRAULIC RESISTANCE OF SUBMERGED VEGETATION RELATED TO EFFECTIVE HEIGHT

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Journal of Hydrodynamics 2010年第2期22卷 265-273页

作者： WANG Pei-fang WANG Chao ZHU David Z. Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of EducationCollege of Environmental Hohai University Nanjing 210098 China Department of Civil and environmental engineering University of Alberta Edmonton Canada T6G 2W2

Submerged vegetation has a significant impact on water flow *** investigations include the impact through adding drag resistance and increasing bottom roughness coefficient,which cannot elucidate the characters of real submerged *** evaluate the effects of submerged vegetation on water currents at different velocities,a laboratory experiment was conducted using three kinds of *** effective heights of these vegetations on varying flow velocities were *** equation describing the relationship between the normalized resistance of the submerged plants and the Reynolds number based on the plant effective height was then established and used to calculate the hydraulic resistance parameters of submerged plants in different stages of growth.

关键词： hydraulic resistance submerged vegetation drag force effective height

Numerical simulation of two-phase turbulent flow in hydraulic and hydropower engineering

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Science china(Technological Sciences) 2007年第z1期50卷 79-89页

作者： DAI HuiChao1,2?, WANG LingLing1, GAO JiZhang3, ZHANG XiaoDong3 & YANG ZhongHua2 1 college of Water Conservancy and Hydropower engineering, hohai university, nanjing 210098, china 2 china Yangtze River Three Gorges Project Development Corporation, Yichang 443002, china 3 china Institute of Water Resources and Hydropower Research, Beijing 100044, china college of Water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China china Yangtze River Three Gorges Project Development Corporation Yichang 443002 China china Institute of Water Resources and Hydropower Research Beijing 100044 China

In connection with the specific features of high velocity aerated flow generated by hydraulic engineering structures, the mathematical model is developed for high turbulence air-water two-phase flow with the use of twin flow theoretical model in this paper. Furthermore the numerical method is proposed to treat bubbled flows. In addition, on the basis of air-water stratified twin flow model, the new calculation methods and free surface tracking technique are proposed to describe complicated movements of the free surface. Finally, the proposed model is used to calculate artificial aerated flows. The computed results coincide quite well with experimental results. This means that the proposed method can provide solid basis for practical engineering design.

关键词： high turbulence two-phase flow twin flow model aerated flow free surface

Non-linear buffeting response analysis of long-span suspension bridges with central buckle

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Earthquake engineering and engineering Vibration 2010年第2期9卷 259-270页

作者： Wang Hao1,2,Li Aiqun1,Zhao Gengwen1 and Li Jian2 1.college of Civil engineering,Southeast university,nanjing 210096,china 2.Civil and environmental engineering,university of Illinois at Urbana-Champaign,Urbana,IL 61801,USA college of Civil engineering Southeast University Nanjing 210096 China

The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in china. By using a spectral representation method and FFT technique combined with measured data,a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented,in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

关键词： suspension bridge buffeting response central buckle nonlinear time history analysis ANSYS

TWO DIMENSIONAL SIMULATION OF WIND-DRIVEN CIRCULATION IN RESERVOIR

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Journal of Hydrodynamics 2003年第3期15卷 112-118页

作者： ChenJie-ren KhalilI.Othman collegeofWaterResourcesandEnvironment HohaiUniversityNanjing210098China collegeofEnvironmentengineering HohaiUniversityNanjing210098China

The development of a simplified 2-D numerical model was described forwind-driven circulation in reservoir u-sing standard k-ε turbulence model to specify eddy viscositydistribution. The governing equations are transformed and solved on variable vertical grids, whichallows refinement at the surface and bottom boundaries. The results of the model simulation for floware compared with analytical solutions for laminar and turbulent flows, experimental data in awind-flume and wind wave tank. The sensitivity analysis results show that use of large number ofdepth layers increases the accuracy for the bottom counter-current flow. Prediction of surface driftwas not very sensitive to surface grid refinement. The model was also applied to Baisha reservoirfor an assumed wind condition and showed to be able to simulate the general features of surfacedrift and return flow under variable flow depth. The model can serve as alternative means ofstudying wind-driven flow beside experiments. It also reduced the problem complexity associated with3-D circulation models while faithfully reproducing the drift and near bottom return currents.

关键词： mathematical modeling wind-driven circulation surface drift countercurrent flow

INFLUENCE OF FILLING WATER ON AIR CONCENTRATION

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Journal of Hydrodynamics 2011年第5期23卷 601-606页

作者： WU Jian-hua MA Fei DAI Hui-chao college of Water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China

The filling water inside the cavity below an aerator occurs for the flow of low Froude number or the small bottom slope of a spillway. The aerator may cease to protect against cavitation damages, and may even act as a generator of cavitation if it is fully filled by water. The experiments were conducted to investigate the influences of the geometric parameters, and then the filling water on the air concentration. The results show that the filling water, or the net cavity length, is closely related to the plunging jet length for a given aerator, and the air concentration at some section is proportional to the ratio Ln/Lj at a fixed Lj for different geometric parameters of aerators. Secondly, at the same ratio of Ln / Lj, the aerator with a larger height or a larger angle of ramp, or a larger bottom slope, would have a larger plunging jet length, and then a larger net cavity length based on the ratio of Ln / Lj. As a result, the large space of cavity, or the high air concentration of the flow could be obtained although the filling water increases also based on the fact that Lf = Lj - Ln. It is the space of the cavity that is the dominant factor to affect the air concentration of the flow.

关键词： aerator air concentration filling water jet length net cavity length

Heterogeneous reaction of NO_2 with sea salt particles

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Science china Chemistry 2010年第12期53卷 2652-2656页

作者： YE ChunXiang 1,LI HongJun 1,ZHU Tong 1,SHANG Jing 1,ZHANG ZeFeng 1,2 & ZHAO DeFeng 1 1 State Key Joint Laboratory of environmental Simulation and Pollution Control college of environmental Sciences and engineering,Peking university,Beijing 100871,china 2.college of Atmospheric Physics,nanjing university of Information Science and Technology,nanjing 210044,china 1. State Key Joint Laboratory of environmental Simulation and Pollution Control college of environmental Sciences and engineering Peking University Beijing 100871 China2. College of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing 210044 China

To understand how NO2 reacts with sea salt particles in the atmosphere of Mega-cities in coastal zones,the heterogeneous reaction of NO2 on the surface of wet sea salt was investigated with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC).Kinetic measurements indicated that nitrate formation on sea salt was second order in NO 2 concentration and reactive uptake coefficients were (5.51 ± 0.19) × 10-7 and 1.26 × 10-6 respectively under 0% and 20% relative humidity (RH) at NO 2 molecular concentration of 1.96 × 1015 mol/*** results showed that liquid water was formed at the site of MgCl2·6H2O,CaCl2·2H2O on the surface of sea salt and made the reaction more sustainable by releasing hydrated water and absorbing water from air even under a low RH (30%).Therefore,pure NaCl particles should not be used to represent sea salt in studies of the heterogeneous reaction with NO2.

关键词： sea salt particles diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) hydrated water absorbed water reactive uptake coefficient

Understanding the endocrine disruption of chiral pesticides:The enantioselectivity in estrogenic activity of synthetic pyrethroids

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Science china Chemistry 2010年第5期53卷 1003-1009页

作者： WANG Cui 1,ZHANG Quan 1,ZHANG XiaoFeng 1,LIU Jing 2 & LIU WeiPing 2 1college of Biological and environmental engineering,Zhejiang university of Technology,Hangzhou 310032,china 2Key Laboratory of environmental Remediation and Ecosystem Health,Ministry of Education college of environmental and Resource Sciences,Zhejiang university,Hangzhou 310029,china 1. college of Biological and environmental engineering Zhejiang University of Technology Hangzhou 310032 China2. Key Laboratory of Environmental Remediation and Ecosystem Health Ministry of Education College of Environmental and Resource Sciences Zhejiang University Hangzhou 310029 China

Synthetic pyrethroids(SPs) ,a family of chiral insecticides consisting of multiple stereoismers,have been regarded as estrogenic endocrine-disrupting chemicals(EDCs) .In this study,we applied the yeast two-hybrid and molecular docking(MD) assay to assess the enantioselective estrogenic activities of three commonly used SPs,bifenthrin(cis-BF) ,permethrin(PM) and fenvalerate(Fen) .The β-galactosidase analyses indicated that all of the testing pyrethroids displayed significant(p2R-Fen and αS-2S-Fen also induced the β-galactosidase *** inability to initiate the reporter gene expression by the racemic chemicals may be due to the low ratios of these isomers or the antagonism among *** strong hydrophobic interaction and the hydrogen bond between positive estrogenic isomers and ERα support our biological testing *** research demonstrated that the enantioselective estrogenic activity of chiral SPs was due to selective binding between their isomers and the ERα*** data suggests that enantioselectivity of these chiral pesticides is significant to their estrogenic activities.

关键词： enantioselectivity synthetic pyrethroids (SPs) endocrine disruption yeast molecular docking

A FIELD TEST DATA RESEARCH BASED ON A NEW HYDRAULIC PARAMETERS QUICK TEST TECHNOLOGY

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Journal of Hydrodynamics 2010年第4期22卷 562-571页

作者： ZHAO Yan-rong ZHOU Zhi-fang School of Earth Sciences and engineering Hohai University Nanjing 210098 China

The hydraulic parameter quick test system in accordance with the oscillation principle can overcome the shortcomings of traditional methods in determining hydraulic parameters which,besides having complex hydrogeological restrictions and needing complex equipment in the field,are often both time and energy consuming,and high *** on the hydrogeological conditions in the north anchorage of Taizhou Yangtze River Highway Bridge,a quick hierarchical test is carried out for different depths of single-hole drilling to verify the function of the system in this ***,with a purification of the raw data gathered in the test by wavelet denoising,the hydraulic parameters are worked out by adopting the Kipp model.A comparison between the Kipp model results and stratigraphic data as well as pumping test results justifies the reliability and accuracy of the new *** study finds other advantages of the method like high efficiency in operation,flexibility in stratified test,as well as ***,the technology is of significant practical value and application prospect.

关键词： hydraulic parameters oscillation principle slug test field test wavelet denoising

NUMERICAL STUDY ON THE THREE-DIMENSIONAL CHARA-CTERISTICS OF THE TIDAL CURRENT AROUND HARBOR ENTRANCE

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Journal of Hydrodynamics 2010年第6期22卷 847-855页

作者： XIE Ming-xiao ZHANG Wei Key Laboratory of engineering Sediment of Ministry of Transport Tianjin Research Institute for Water TransportEngineering M.O.T. Tianjin 300456 China college of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China

A three-dimensional （3-D） numerical model is established to investigate the tidal current motion characteristics around the harbor entrance. Computational approaches consist of the finite difference method, time-splitting technique, C-grid, and a high-order turbulence closure model. The Ocean General Circulation Model （OGCM） inundation scheme is incorporated in the model. An engineering application, Lianyungang Harbor, china, is used as a real-life case. The model is validated by showing that the simulated results agree well with the field data. In the approach channel, the tidal current shows a deflection effect especially in the bottom layer. As for Lianyungang Harbor, a jet flow forms at the tip of the northern breakwater, which drives a circulation flow at the inner side of the harbor entrance. In the vertical, the flow is significantly stratified at the entrance section within the channel, where the flow direction varies between layers and the speed distribution is quite uniform. These 3-D features become less evident to the offshore. Additionally, the sensitivity analysis shows that the flow deflection is related to the channel depth. Simulation results also imply that the siltation rate at the entrance section of the approach channel tends to be more uniform by the 3-D flow motion feature, and could be more significant with the increase of the channel depth.

关键词： 3-D model harbor entrance OGCM inundation scheme stratification features