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Doubly Periodic Wave Solutions of Jaulent-Miodek Equations Using Variational Iteration Method Combined with Jacobian-function Method

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Communications in Theoretical Physics 2008年第6期49卷 1403-1406页

作者： ZHU Jia-Min lu zhi-ming LIU Yu-lu Department of Computer Yiwu Industrial and Commercial College Yiwu 322000 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

One of the advantages of the variational iteration method is the free choice of initial guess. In this paper we use the basic idea of the Jacobian-function method to construct a generalized trial function with some unknown parameters. The Jaulent-Miodek equations are used to illustrate effectiveness and convenience of this method, some new explicit exact travelling wave solutions have been obtained, which include bell-type soliton solution, kink-type soliton solutions, solitary wave solutions, and doubly periodic wave solutions.

关键词： Jaulent-Miodek equations Jacobian-function method variational iteration method doubly periodic wave solution exact solution

EFFECT OF SWEEP AND EJECTION EVENTS ON PARTICLE DISPERSION IN WALL BOUNDED TURBULENT FLOWS

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Journal of Hydrodynamics 2012年第5期24卷 794-799页

作者： luO Jian-ping lu zhi-ming QIU Xiang LI Dong-mei LIU Yu-lu School of Mechanical Engineering Shanghai Institute of Technology Shanghai 200235 China Shanghai Key Laboratory of Mechanics in Energy Engineering and Shanghai Institute of Applied Mathematicsand Mechanics Shanghai University Shanghai 200072 China School of Science Shanghai Institute of Technology Shanghai 200235 China Shanghai Institute of Technology Shanghai 200235 China

This paper studies the sweep and ejection events in a channel flow with Reτ = 80 by using Direct Numerical Simulation （DNS）. The effects of ejection and sweep events on the transport of fluid particles are analyzed separately through a quadrant technique. By analyzing trajectories of the particles released at different wall-normal locations, it is found that the particles from the ejection events mainly move upward while the particles from the sweep events move downward of the flow during short and intermediate diffusion time durations. Numerical results show that the effects of the ejection and sweep events on the mean displacement and the mean square dispersion remain for a long time, one-order of magnitude larger than the streamwise Lagrangian integral ~cales.

关键词： sweep ejection dispersion quadrant analysis turbulent channel flow

Solitons and Waves in （2＋l）-Dimensional Dispersive Long-Wave Equation

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Communications in Theoretical Physics 2006年第5X期46卷 799-803页

作者： MA Zheng-Yi LIU Yu-lu lu zhi-ming ZHENG Chun-Long2lu zhi-ming,1 and ZHENG Chun-Long Shaaghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Department of Mathematics Zhejiang Lishui University Lishui 323000 China

For a higher-dimensional integrable nonlinear dynamical system, there are abundant coherent soliton excitations. With the aid of an improved projective Riccati equation approach, the paper obtains several types of exact solutions to the （2＋l）-dimenslonal dispersive long-wave equation, including multiple-soliton solutions, periodic soliton solutions, and Weierstrass function solutions. From these solutions, apart from several multisoliton excitations, we derive some novel features of wave structures by introducing some types of lower-dimensional patterns.

关键词： (2+l)-dimensional dispersive long-wave equation projective Riccati equation approach soliton annihilation traveling wave

SIMULATION OF LAGRANGIAN DISPERSION USING A LAGRANGIAN STOCHASTIC MODEL AND DNS IN A TURBULENT CHANNEL FLOW

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Journal of Hydrodynamics 2009年第6期21卷 767-773页

作者： luO Jian-ping lu zhi-ming LIU Yu-lu School of Mechanical and Automation Engineering Shanghai Institute of Technology Shanghai 200235 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

The mean square displacements of fluid particles in a turbulent channel flow at Reτ = 100 are investigated using a modified Langevin equation, and are compared with DNS results. Both the Lagrangian integral time scales directly obtained from DNS and the predicted values using an empirical relation between the Eulerian and the Lagrangian integral time scales are used in the modified Langevin equation to test the effects of integral time scales on the dispersion of particles. The results show that the slight variation of the Lagrangian integral time scale has little influence on the dispersion. The agreement between results of the model equation and those of DNS is satisfactory except the streamwise dispersion for intermediate times （ 20 〈 t^＋〈 300 ）, where the results of the model equation are slightly overestimated compared to those of DNS. The cause of such discrepancy is discussed.

关键词： turbulent channel flow Lagrangian dispersion Lagrangian stochastic model

THE EXTENDED JACOBIAN ELLIPTIC FUNCTION EXPANSION METHOD AND ITS APPLICATIONS IN WEAKLY NONLINEAR WAVE EQUATIONS

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Journal of Hydrodynamics 2006年第3期18卷 352-361页

作者： HUANG Wen-hua LIU Yu-lu lu zhi-ming PAN Bo-ying LIU Mao-sheng Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Department of Physics College of Science Huzhou University Huzhou 313000 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China PAN Bo-ying Basic Department YiChun Vocational Technical College Yichun 336000 China

The extended Jacobian elliptic function expansion method is introduced and applied to solve the coupled ZK equations and the coupled KP equations describing two weakly long nonlinear wave models in fluid system. Many types of doubly periodic traveling wave solutions are obtained. Under limiting conditions these solutions are reduced into solitary wave solutions.

关键词： Jacobian elliptic function expansion method,the coupled ZK equation the coupled KP equation

TURBULENT MIXING AND EVOluTION IN A STABLY STRATIFIED FLOW WITH A TEMPERATURE STEP

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Journal of Hydrodynamics 2009年第1期21卷 84-92页

作者： QIU Xiang ZHANG Dao-xiang lu zhi-ming LIU Yu-lu Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Department of Mathematics Shanghai University Shanghai 200444 China

Large-Eddy Simulation （LES） is applied to examine the turbulent mixing and evolution in a stably stratified flow with a thermally sharp interface. Turbulent velocity intensities and turbulent kinetic energy are analyzed by considering the mean shear and stratification effects. The evolution of turbulent mixing layer and turbulent structures are mainly investigated. The results show that the streamwise intensities are much larger than the vertical intensities, and vertical fluctuations decay more rapidly at the presence of stratification. The qualitatively computational results suggest that the mixing layer, defined by the mean temperature, inclines to the side with small inlet velocity. The evolution of the half-width of the mixing layer shows two different slopes. The turbulent structure with high vorticity is restricted in the mixing layer especially in strong stratified cases.

关键词： stratified turbulence turbulent mixing turbulent structure Large-Eddy Simulation (LES)

NUMERICAL SIMULATION OF THE DISPERSION IN OSCILLATING FLOWS WITH REVERSIBLE AND IRREVERSIBLE WALL REACTIONS

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Journal of Hydrodynamics 2009年第4期21卷 482-490页

作者： ZHANG Dao-xiang lu zhi-ming LIU Yu-lu NG Chiu-On Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China College of Mathematics and Computer Science Anhui Normal University Wuhu 241000 China Department of Mechanical Engineering The University of Hong Kong Hong Kong China

This is a study on the mass transport of a solute or contaminant in oscillating flows through a circular tube with a reactive wall layer. The reaction consists of a reversible component due to phase exchange between the flowing fluid and the wall layer, and an irreversible component due to absorption into the wall. The short-time dispersion characteristics are numerically investigated, incorporating the coupling effects between the flow oscillation, sorption kinetics, and retardation due to phase partitioning. The effects of various dimensionless parameters e.g., Da （the Damkoehler number）, α （phase partitioning number）, F （dimensionless absorption number）, and δ （dimensionless Stokes boundary layer number） on dispersion are discussed. In particular, it is found that there exist trinal peaks of the breakthrough curves in some cases.

关键词： dispersion flow oscillation wall reactions

Expressing p20 hairpin RNA of Citrus tristeza virus confers Citrus aurantium with tolerance/resistance against stem pitting and seedling yellow CTV strains

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Journal of Integrative Agriculture 2015年第9期14卷 1767-1777页

作者： CHENG Chun-zhen YANG Jia-wei YAN Hu-bin BEI Xue-jun ZHANG Yong-yan lu zhi-ming ZHONG Guang-yan College of Horticulture and Landscape Architecture Southwest University Institute of Fruit Tree Research Guangdong Academy of Agricultural Sciences Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization Ministry of Agriculture Economic Crops Station Agricultural Bureau of Rongxian Institute of Crop Science Shanxi Academy of Agricultural Sciences

The Citrus tristeza virus (CTV) uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strat-egies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA frag-ments from the three genes, and used them to construct vectors for expressing hairpin RNAs (hpRNAs). To facilitate the formation of hpRNAs, the constructs were introduced in a loop structure. Fol owing transformation of sour orange (Citrus aurantium) with these constructs, 8 p20 hpRNA (hp20) and 1 p25 hpRNA (hp25) expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested fol owing inoculation with CT14A and/or TR-L514, both of which are severe strains. Results showed that 3 lines (hp20-5, hp20-6 and hp20-8) were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently chal enged with CT14A. These results showed that expressing p20 hpRNA was sufifcient to confer sour orange with CTV resistance/tolerance.

关键词： Citrus tristeza virus(CTV) RNA interference transgenic plant Citrus aurantium disease resistance

Detrended analysis of Reynolds stress in a decaying turbulent flow in a wind tunnel with active grids

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Journal of Hydrodynamics 2014年第1期26卷 122-128页

作者： AHMAD Imtiaz 黄永祥卢志明 Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Department of Mathematics University of Azad Jammu and Kashmir Shanghai Institute of Applied Mathematics and Mechanics and Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

Multi-scale properties of Reynolds stress in decaying turbulence in a wind tunnel with high Reynolds number are investi-gated. Two filtering techniques i.e., the zeroth-order and first-order detrending methods are applied to the two velocity components, where the local mean value （resp. local linear trend） is removed in the former （latter） technique. Some basic statistics for thirty mea-surements show that the variation is very large at first two locations and relatively small at last two locations. Moderately good power law is found for the mean value of local Reynolds stress at last three measurement locations with scaling exponents approxi-mately being 1.0 and a dual power law exists for the mean value of standard deviation of local Reynolds stress at all four measureme-nt locations with scaling exponents being 0.53 and 0.58 for zeroth-and first-order filtering respectively. Present results about local Reynolds stress are useful to build and evaluate the model of sub-grid Reynolds stress in large eddy simulations.

关键词： Reynolds stress multi-scale analysis detrended analysis power law