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Initial Dilution of A Vertical Round Non-Buoyant Jet in Wavy Cross-Flow Environment

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China Ocean Engineering 2015年第6期29卷 847-858页

作者：王娅娜陈永平徐振山潘毅张长宽李志伟 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Harbor Coastal and Offshore Engineering Hohai University Department of Civil and Environmental Engineering The Hong Kong Polytechnic University

The phenomenon of wastewater discharged into coastal waters can be simplified as a turbulent jet under the effect of waves and currents. Previous studies have been carried out to investigate the jet behaviors under the current only or the wave only environment. To obtain better understanding of the jet behaviors in a realistic situation, a series of physical experiments on the initial dilution of a vertical round jet in the wavy cross-flow environment are conducted. The diluted processes of the jet are recorded by a high-resolution camcorder and the concentration fields of the jet are measured with a peristaltic suction pumping system. When the jet is discharged into the wavy cross-flow environment, a distinctive phenomenon, namely ＂effluent clouds＂, is observed. According to the quantitative measurements, the jet width in the wavy cross-flow environment increases more significantly than that does in the cross-flow only environment, indicating that the waves impose a positive effect on the enhancement of jet initial dilution. In order to generalize the experimental findings, a comprehensive velocity scale ua and a characteristic length scale l are introduced. Through dimensional analysis, it is found that the dimensionless centerline concentration trajectories cy/l is in proportion to 1/3 power of the dimensionless downstream distance x/l, and the dimensionless centerline dilution 2c aS Q/（u l） is proportional to the square of the dimensionless centerline trajectory cy/l. Several empirical equations are then derived by using the Froude number of cross-flow Frc as a reference coefficient. This paper provides a better understanding and new estimations of the jet initial dilution under the combined effect of waves and cross-flow current.

关键词： turbulent jet initial dilution wavy cross-flow environment experimental study dimensional analysis

Scaling laws of compressible turbulence

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Applied Mathematics and Mechanics(English Edition) 2017年第6期38卷 765-778页

作者： Bohua SUN Department of Mechanical Engineering Cape Peninsula University of Technology Cape Town 7535 South Africa

Spatial scaling laws of velocity kinetic energy spectra for the compressible turbulence flow and the density-weighted counterparts are formulated in terms of the wavenumber, dissipation rate, and Mach number by using a dimensional analysis. We apply the Barenblatt＇s incomplete similarity theory to both kinetic and density-weighted energy spectra. It shows that, within the initial subrange, both energy spectra approach the -5/3 and -2 power laws of the wavenumber when the Mach number tends to unity and infinity, respectively.

关键词： compressible turbulence spatial scaling law dimensional analysis incom-plete similarity

Effect of projectile parameters on opening behavior of PELE penetrating RC target

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Defence Technology（防务技术） 2021年第3期17卷 859-873页

作者： Li-zhi Xu Cheng-xin Du Chun Cheng Xiao-dong Wang Jiang-bo Wang Zhong-hua Du Guang-fa Gao School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China

When a penetrator with enhanced lateral effect(PELE) impacts on a reinforced concrete(RC) target,the target is damaged with a large opening.An understanding of how PELE projectile parameters affect the opening dimension,is essential for effective design of the PELE projectile.In this study,under the condition that the impact velocity and target parameters(strength and thickness) were fixed values,the important influence factors of the PELE(jacket wall thickness B,jacket material strength Y1,filling material strength Y2 and angle of monolithic jacket θ) were determined by a dimensional analysis.Tests and simulations of the PELE penetrating the RC target were conducted to analyze the influence of these factors on opening diameter(D,an equivalent diameter under relative kinetic energy).Based on the test and simulation results,it is found that the influence of these factors B,Y1 and θ on the deformation mode of the jacket shows a similar trend:as values of the three factors decrease,the jacket deforms from small bending deformation to large one,and then to curling deformation.This causes the opening diameter to first increase with the decrease of these three factors,and then decreases.It is well known that the bending resistance of the jacket is related to these factors B,Y1 and θ.Therefore,a plastic limit bending moment(M0) of the jacket was quoted to characterize the influence of these factors on the bending deformation of the jacket and the opening diameter of the target.The influence factor Y2 causes D to first increase with the increase of Y2,and then decreases.A formula was developed to predict the opening diameter,whose influence parameters were considered in a dimensionless way.It has been shown that the dimensionless opening diameter D/d1 is dependent on two dimensionless parameters■ and■,where d1 and fc are the outer diameter of the projectile and the compressive strength of the target,respectively.

关键词： Penetrator with enhanced lateral effect Opening behaviour Reinforced concrete target dimensional analysis

Physical Property Influence on Foaming Index of Refining Slag

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 8-10,14页

作者： Lin Di Ping Wang Jie Fu (Metallurgy School, University of Science and Technology Beijing, Beijing 100083, China) Univ of Science and Technology Beijing Beijing China

The foaming indexes of a group of refining slag were measured. The refining slag with better foaming ability was chosen,its composition (mass frachon in %) is CaO, 53.25, SiO2, 17.75, MgO, 9; Al2O3, 15 and CaF2, 5. The relationship between slag foaming index and physical properties of the slag was obtained by dimensional analysis, and the expression indicates that viscosity of slag is the most important factor which influences foamng index. The influence sequence of slap composition on foaming index was also obtained as follows: CaF2→MgO→Al2O3→ B (CaO/SiO2).

关键词： secondary refining submerged arc slag dimensional analysis

Scaling relationships of elastic-perfectly plastic film/coating materials from small scale sharp indentation

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Science China(Technological Sciences) 2021年第6期64卷 1302-1310页

作者： WANG ZhaoXin WANG JiRu WANG Wen Yang NIU YiHan LI Cong ZONG XiangYu ZHANG JianHai ZHAO HongWei Key Laboratory of CNC Equipment Reliability Ministry of EducationJilin UniversityChangchun 130025China School of Mechanical&Aerospace Engineering Jilin UniversityChangchun 130025China

The scaling relationships of elastic-perfectly plastic film/coating materials during sharp indentation have been obtained using dimensional analysis and finite-element modeling. Besides the bulk substrate materials, a wide range of film/coating materials with different ratios in term of the Young’s modulus and yield strength were examined, namely different values of Ef/Esand Yf/Es.Based on these scaling relationships, the substrate effects on indentation response and deformed surface profile of residual imprint are given. Furthermore, the scaling relationship among the work of indentation, reduced elastic modulus and hardness has been found. It is found that the ratio of the indentation hardness to measurement of substrate elastic modulus could be used to characterize the wear resistance of film/coating materials. In addition, a novel method to acquire the intrinsic hardness and elastic modulus of film/coating materials is proposed combined with the well-known 10% critical indentation depth rule, which avoids the error caused by estimating the contact area. This work could be contributed for characterizing the mechanical properties of film/coating materials at micro-and nanoscale.

关键词： scaling relationships substrate effect dimensional analysis finite element modeling film/coating materials indentation

HYDRAULIC CHARACTERISTICS OF WATER-WINGS FOR THE MIDDLE-PIER OF A DISCHARGE TUNNEL

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Journal of Hydrodynamics 2006年第5期18卷 567-571页

作者： WU Jian-hua CAI Chang-guang JI Wei RUAN Shi-ping College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China China Hydropower Mid-South Design and Research Institute Changsha 410014 China

Water-wings, induced by the middle-pier placed in the inlet of a discharge tunnel, have harmful effects on the operation of the discharge tunnel. Based on dimensional analysis and physical model tests, the hydraulic characteristics of water-wings were investigated and their causes were analyzed in this study. The results show that the height and length of the water-wings increased with the increase of three factors, i.e., the Froude number Frd of the outlet of the pressure section, the depth Hc of the water surface concave at the end of the middle-pier, and the impact length Li of the two flows after this end.

关键词： water-wing dimensional analysis discharge tunnel middle-pier

How Properties that Distinguish Solids from Fluids and Constraints of Spherical Geometry Suppress Lower Mantle Convection

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Journal of Earth Science 2018年第1期29卷 1-20页

作者： Anne M. Hofmeister Everett M. Criss Department of Earth and Planetary Sciences Washington University St. Louis MO 63130 USA Panasonic Avionics Corporation Lake Forest CA 92630 USA

The large magnitude of the dimensionless Rayleigh number （Ra-10^8） for Earth＇s -3 000 km thick mantle is considered evidence of whole mantle convection. However, the current formulation assumes behavior characteristic of gases and liquids and also assumes Cartesian geometry. Issues arising from neglecting physical properties unique to solids and ignoring the spherical shapes for planets include：（1） Planet radius must be incorporated into Ra, in addition to layer thickness, to conserve mass during radial displacements. （2） The vastly different rates for heat and mass diffusion in solids, which result from their decoupled transport mechanisms, promote stability. （3） Unlike liquids, sub- stantial stress is needed to deform solids, which independently promotes stability. （4） High interior compression stabilizes the mantle in additional minor ways. Therefore, representing conditions for convection in solid, self-gravitating spheroids, requires modifying formulae developed for bottom- heated fluids near ambient conditions under an invariant gravitational field. To derive stability criteria appropriate to solid spheres, we use dimensional analysis, and consider the effects of geometry, force competition, and microscopic behavior. We show that internal heating has been improperly ac- counted for in the Ra. We conclude that the lower mantle is stable for two independent reasons： heat diffusion far outpaces mass diffusion （creep） and yield strength of solids at high pressure exceeds the effective deviatoric stress. We discuss the role of partial melt in lubricating plate motion, and explain why the Ra is not applicable to the multi-component upper mantle. When conduction is insufficient to transport heat in the Earth, melt production and ascent are expected, not convection of solid rock.

关键词： plasticity diffusion mantle convection stability criteria dimensional analysis geometry.

The effects of hydrogen bonding on the shear viscosity of liquid water

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International Journal of Sediment Research 2019年第1期34卷 8-13页

作者： Hongwei Fang Ke Ni Jian Wu Jun Li Lei Huang Danny Reible State Key Laboratory of Hydro-science and Engineering Department of Hydraulic EngineeringTsinghua University State Key Laboratory of Low-dimensional Quantum Physics Department of PhysicsTsinghua University Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of ChemistryTsinghua University Department of Civil & Environmental Engineering Texas Tech University

As one of the fundamental physical properties of fluids, viscosity is considered to be the result of intermolecular forces and molecular momentum exchange. In this paper, we assume that hydrogen bonds, as the dominant intermolecular force, dominate the shear viscosity of liquid water and a relationship between the shear viscosity and hydrogen bonding is developed using dimensional analysis,which is further validated by computational chemistry methods. Water, methanol and ethanol are taken as examples to illustrate shear viscosity accounting for intermolecular forces and momentum exchange and their temperature dependence as a result of molecular thermal motions. The calculated shear viscosity of water is consistent with experimental data, which supports the idea that we can use the conceptual model to reveal the nature of shear viscosity.

关键词： Viscosity Hydrogen bonding Liquid water dimensional analysis

Experimental evaluation of the effect of storm movement on peak discharge

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International Journal of Sediment Research 2015年第2期30卷 167-177页

作者： Jin Liang Charles S.Melching Department of Civil Construction and Environmental EngineeringMarquette University

The hypothesis that downstream moving storms with storm length less than watershed length（L;/L< 1.0） magnify the peak discharges as indicated by kinematic-wave models in previous studies was evaluated in an analysis... 详细信息

The hypothesis that downstream moving storms with storm length less than watershed length（L;/Lanalysis of the dimensionless peak discharge and dimensionless storm velocity.Previously unpublished experimental data collected for a V-shaped watershed in the Watershed Experimentation System（WES） at the University of Illinois at Urbana-Champaign,were used in comparison with the simulation results of a kinematic-wave model.It is found that downstream moving storms with L;/L < 1.0 increase the peak discharges to a limited extent compared to stationary storms,and the kinematic-wave model overstates the increase in the peak flows resulting from downstream moving storms with L;/L < 1.0.To evaluate the importance of the backwater effects in the experimental watershed,the accuracy of kinematic-wave and dynamic-wave models for the simulation of surface runoff resulting from upstream and downstream moving storms was evaluated utilizing the same experimental data.The kinematic-wave model simulates the upstream moving storms pretty well,i.e.Nash-Sutcliffe coefficient of model fit efficiency equal to 0.948 and 0.831 for storms lengths equal to and not equal to the watershed length,respectively.Whereas,the kinematic wave model substantially overestimates the peak discharge of downstream moving storms,and yields generally poorer fits than for upstream moving storm,i.e.NSE equal to 0.867 and 0.674 for storms with lengths equal to and not equal to the watershed length,respectively.The dynamic-wave model simulates the downstream moving storms pretty well,i.e.NSE equal to 0.843 and 0.879 for storms with lengths equal to and not equal to the watershed length,respectively,indicating backwater significantly affects runoff for even this simple experimental watershed.Considering that storm movement did not substantially magnify peak discharge,the assumption of stationary storms made in standard hydrologic design seems reasonable

关键词： Moving storms Kinematic-wave Dynamic-wave Experimental data dimensional analysis