检索结果-南通市图书馆

A NOTE ON THE COMPLEX DISPERSION RELATION FOR STEADY VISCOUS SHIP WAVES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2005年第1期17卷 22-26页

作者： LUDong-qiang shanghaiinstituteofappliedmathematicsandmechanics ShanghaiUniversityShanghai200072China／／DepartmentofMechanicalEngineeringTheUniversityofHongKongHongKongChina

Based on the double Fourier integral representation for steady viscous ship waves, which involves a generic amplitude function and a complex dispersion relation, the phase function for three dimensional ship waves in the far field was asymptotically derived by means of the Lighthill two stage scheme combining the Cauchy residue theorem and the method of steepest descents, and the effect of viscosity on wavelengths was numerically investigated with the Newton iteration method. It is found that the transverse and diverging waves are elongated due to the presence of viscosity and the latter is more heavily affected and that the phase differences between the viscous transverse and diverging waves are larger than those of the corresponding inviscid waves.

关键词： free-surface wave Oseen flow viscosity complex dispersion relation

PIV MEASUREMENTS OF THE NEAR-WAKE FLOW OF AN AIRFOIL ABOVE A FREE SURFACE

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第4期19卷 482-487页

作者： Daichin KANG Wen ZHAO Li-li shanghai institute of applied mathematics and mechanics Shanghai University Shanghai 200072 China Rapid Manufacturing Engineering Center Shanghai University Shanghai 200444 China

The near-wake flow of a NACA0012 airfoils mounted above a water surface were experimentally studied in a wind/wave tunnel. The main objective of this study is to investigate the influence of the free surface on the structure of the airfoil trailing wake. The flow structure was measured with different ride heights between the airfoil and free surface using a Particle Image Velocimetry （PIV） system. The Reynolds number based on the chord length of the airfoil was about 3.5×10^3. For each experimental condition, large amount of instantaneous velocity fields were captured and ensemble-averaged to get the spatial distributions of mean velocity and mean vorticity, as well as turbulence statistics. The results show that the flow structures of the airfoil wake varies remarkably with the change in the ride height.

关键词： wing-in-ground effect NACA0012 airfoil free surface wake flow Particle Image Velocimetry (PIV) measurement

FLEXURAL-GRAVITY WAVES DUE TO TRANSIENT DISTURBANCES IN AN INVISCID FLUID OF FINITE DEPTH

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第2期20卷 131-136页

作者： LU Dong-qiang LE Jia-chun DAI Shi-qiang shanghai institute of applied mathematics and mechanics Shanghai University Shanghai 200072 China shanghai Key Laboratory of mechanics in Energy and Environment Engineering Shanghai 200072 China

The dynamic response of an ice-covered fluid to transient disturbances was analytically investigated by means of integral transforms and the generalized method of stationary phase. The initially quiescent fluid of finite depth was assumed to be inviscid, incompressible, and homogenous. The thin ice-cover was modeled as a homogeneous elastic plate. The disturbances were idealized as the fundamental singularities. A linearized initial-boundary-value problem was formulated within the framework of potential flow. The perturbed flow was decomposed into the regular and the singular components. An image system was introduced for the singular part to meet the boundary condition at the fiat bottom. The solutions in integral form for the vertical deflexion at the ice-water interface were obtained by means of a joint Laplace-Fourier transform. The asymptotic representations of the wave motion were explicitly derived for large time with a fixed distance-to-time ratio. The effects of the finite depth of fluid on the resultant wave pattems were discussed in detail. As the depth increases from zero, the critical wave number and the minimal group velocity first increase to their peak values and then decrease to constants.

关键词： waves ice-cover transient disturbances asymptotic group velocity

Transverse patterns and spatiotemporal instability of a photorefractive oscillator

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1997年第9期42卷 724-729页

作者： ZHUANG Jun and TAN Weihan1. shanghai institute of Optics and Fine mechanics, Chinese Academy of Sciences, shanghai 201800, china 2. shanghai University, shanghai 201800, china shanghai institute of Optics and Fine mechanics Chinese Academy of Sciences Shanghai China shanghai University Shanghai China

IN time realm,instability and chaos phenomena of a nonlinear optical system have been dis-cussed *** recent years,as much interest was attracted to the transverse ef-fects in nonlinear optics,the study was developed t... 详细信息

关键词： photorefractive oscillator spatiotemporal instability transverse patterns.

Generalized dromion solutions of a new higher dimensional soliton equation

在线全文

学校读者我要写书评

暂无评论

Communications in Nonlinear Science and Numerical Simulation 2001年第2期6卷 97-101页

作者： Jiefang ZHANG and Gongdi XU shanghai institute of applied mathematics and mechanics, shanghai 200072, china institute of Nonlinear Physics, Zhejiang Normal University, Jinhua 321004, china College of Chemical Engineering, Qiqihar University, Qiqihar 161 shanghai institute of applied mathematics and mechanics Shanghai 200072 China institute of Nonlinear Physics Zhejiang Normal University Jinhua 321004 China College of Chemical Engineering Qiqihar University Qiqihar161000 China

We derive the generalized dromions of the new higher dimensional soliton equation by suitably utilizing the arbitrary function present in the bilinearized linear equations. The rich dromion structures for this system ... 详细信息

关键词： dromion soliton equation

Conjugation in Representations of the Zassenhaus Algebra

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2001年第2期17卷 319-326页

作者： Bin SHU institute of applied mathematics & Physics. shanghai Maritime University. shanghai 200135, P. R. china institute of applied mathematics & Physics Shanghai Maritime University Shanghai 200135 P. R. China

Let F be an algebracially closed field of characteristic p>2, and L be the pn-dimensional Zassenhaus algebra with the maximal invariant subalgebra L0 and the standard filtration {Li}|i=-1pn-2. Then the number of isomorphism classes of simple L-modules is equal to that of simple L0-modules, corresponding to an arbitrary character of L except when its height is biggest. As to the number corresponding to the exception there was an earlier result saying that it is not bigger than pn.

关键词： Zassenhaus algebras (Cartan-type Lie algebras) Simple modules of Lie algebras and their isomorphism classes

Localized Structures on Periodic Background Wave of (2+1)-Dimensional Boiti-Leon-Pempinelli System via an Object Reduction

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2007年第11期48卷 811-814页

作者： FANG Jian-Ping MA Song-Hua FEI Jin-Xi HONG Bi-Hai ZHENG Chun-Long College of mathematics and Physics,Lishui University,Lishui 323000,china shanghai institute of applied mathematics and mechanics,shanghai University,shanghai 200072,china College of mathematics and Physics Lishui University Lishui 323000 China shanghai institute of applied mathematics and mechanics Shanghai University Shanghai 200072 China

In this paper,we present an object reduction for nonlinear partial differential *** a concreteexample of its applications in physical problems,this method is applied to the (2+1)-dimensional Boiti-Leon-Pempinellisystem,which has the extensive physics background,and an abundance of exact solutions is derived from some *** on the derived solutions,the localized structures under the periodic wave background are obtained.

关键词： object reduction (2+1)-dimensional Boiti-Leon-Pempinelli system exact solution

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

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

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

NUMERICAL SIMULATIONS OF NONLINEAR WAVES OVERTOPPING AN OBSTRUCTION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 1999年第4期11卷 104-109页

作者： Wan De cheng shanghai institute of applied mathematics and mechanics, shanghai University, shanghai 200072, P.R.china shanghai institute of applied mathematics and mechanics Shanghai UniversityShanghai 200072 P.R.China

The flows of nonlinear waves overtopping an obstruction are studied numerically in the present paper. The finite difference method is used to solve the full two dimensional Navier Stokes equations, and the VOF method is adopted to deal with free surface deformations. Numerical results of a solitary wave and periodic waves overtopping an rectangular cylinder are obtained respectively. Many complex phenomena, such as water accumulation, wave run up, water jet flows, water jet impact both upon free surface and on a structure, and generation of new waves on the lee side during the process of the waves overtopping an obstacle, can be successfully simulated.

关键词： nonlinear waves overtopping. VOF method