检索结果-南通市图书馆

An improved boundary element method for modelling a self-reacting point absorber wave energy converter

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第6期34卷 1015-1034页

作者： Qian-Long Xu Ye Li Zhi-Liang Lin State Key Laboratory of Ocean Engineering Collaborative Innovation Center for Advanced Ship and Deep-Sea ExplorationMuti-function Towing TankKey Laboratory of Hydrodynamics(Ministry of Education)School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

A numerical model based on a boundary element method (BEM) is developed to predict the performance of two-body selfreacting floating-point absorber (SRFPA) wave energy systems that operate predominantly in *** key numerical issues in applying the BEM are systematically *** particular,some improvements and simplifications in the numerical scheme are developed to evaluate the free surface Green's function,which is a main element of difficulty in the *** a locked SRFPA system,the present method is compared with the existing experiment and the Reynolds-averaged NavierStokes (RANS)-based method,where it is shown that the inviscid assumption leads to substantial over-prediction of the heave *** the unlocked SRFPA model we study in this paper,the additional viscous damping primarily induced by flow separation and vortex shedding,is modelled as a quadratic drag force,which is proportional to the square of body *** inclusion of viscous drag in present method significantly improves the prediction of the heave responses and the power absorption performance of the SRFPA system,obtaining results excellent agreement with experimental data and the RANS simulation results over a broad range of incident wave periods,except near resonance in larger wave height *** is found that the wave overtopping and the re-entering impact of out-of-water floating body are observed more frequently in larger waves,where these non-linear effects are the dominant damping sources and could significantly reduce the power output and the motion responses of the SRFPA system.

关键词： Boundary element method Floating-point absorber Heave Green's function viscous drag

A lubricant boundary condition for a biological body lined by a thin heterogeneous biofilm

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Biomathematics 2019年第1期12卷 43-69页

作者： Mustapha El Jarroudi Riane Hajjami Aadil Lahrouz Moussa El Jarroudi Department of Mathematics Laboratory of Mathematics and Applications Abdelmalek Essaadi University TangierB.P.416Morocco Department of Environmental Sciences and Management Liege University ArionB-6700Belgium

We study the asymptotic behavior of an incompressible viscous fluid flow in a biological body lined by a thin biological film with a cellular microstructure,varying thickness,and a heterogeneous viscosity regulated by a time random *** ting the thickness of the film tend to zero,we derive an effective biological slip boundary condition on the boundary of the *** law relates the tangential fluxes to the tangential velocities via a proportional coefficient corresponding to the energy of some local *** law describes the ability of the biological film to function as a lubricant reducing friction at the wall of the *** tangential velocities are functions of the random trajectories of a finely concentrated biological particle.

关键词： Biological body incompressible viscous flow thin biofilm flow random structural evolution asymptotic analysis lubricant effective boundary condition

Dynamic Stress and Pore Pressure Around Circular Cavity in Saturated Porous Elastic Half-space Under Harmonic Plane Dilatational Waves

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2006年第4期11卷 506-511页

作者：姜领发王建华周香莲 School of Naval Architecture Ocean & Civil Eng. Shanghai Jiaotong Univ.

Dynamic stress concentration and pore pressure concentration around an infinitely long cylindrical cavity of circular cross-section subjected to harmonic plane dilatational waves in fluid-saturated porous elastic half-space were obtained by a complex function method based on potential function and multi-polar coordinate. The steady state Biot’s dynamic field equations of porous elastic solid with a viscous liquid were uncoupled into Helmholtz equations via given potential functions. A circular cavity with large radius is used to replace the straight boundary of the saturated porous elastic half-space. The stresses and pore pressures were obtained by using complex functions in multi-polar coordinates with certain boundary conditions of the solid matrix and the fluid matrix. The approximate solutions were compared to existing numerical solutions. Then the variations of the coefficients of dynamic stress concentration and the pore pressures concentration on boundaries of the cavity were discussed with different parameter conditions. The results of the given numerical example indicate that the method used is useful and efficient to the scattering and dynamic stress concentration of plane dilatational waves in saturated porous elastic half-space.

关键词： multi-polar coordinate saturated porous elastic half-space viscous complex function cavity

Empirical mode decomposition of multiphase flows in porous media:characteristic scales and speed of convergence

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2020年第1期17卷 153-167页

作者： Nicolás Echebarrena Pablo D.Mininni Gustavo A.Moreno YPF-Technology EnsenadaBuenos AiresArgentina CONICET Buenos AiresArgentina Physics Department IFIBASchool of Exact and Natural SciencesUniversity of Buenos AiresCONICETUniversity Campus1428 Buenos AiresArgentina

We apply a proper orthogonal decomposition(POD)to data stemming from numerical simulations of a fingering instability in a multiphase flow passing through obstacles in a porous medium,to study water injection processes in the production of hydrocarbon *** show that the time evolution of a properly defined flow correlation length can be used to identify the onset of the fingering *** of characteristic lengths for each of the modes resulting from the POD provides further information on the dynamics of the ***,using numerical simulations with different viscosity ratios,we show that the convergence of the POD depends non-trivially on whether the fingering instability develops or *** result has implications on proposed methods to decrease the dimensionality of the problem by deriving reduced dynamical systems after truncating the system’s governing equations to a few POD modes.

关键词： Two-phase flow Empirical mode decomposition viscous fingering Porous media

Chiral phase structure of the sixteen meson states in the SU(3) Polyakov linear-sigma model for finite temperature and chemical potential in a strong magnetic field

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2019年第3期43卷 56-71页

作者： Abdel Nasser Tawfik Abdel Magied Diab M.T.Hussein Nile University Juhayna sq.of 26th-July-Corridor16453 GizaEgypt Frankfurt Institute for Advanced Studies Ruth Moufang Str.160438 FrankfurtGermany and World Laboratory for Cosmology And Particle Physics(WLCAPP)11571 CairoEgypt Egyptian Center for Theoretical Physics(ECTP) MTI University11571 CairoEgypt and World Laboratory for Cosmology And Particle Physics(WLCAPP)11571 CairoEgypt Physics Department Faculty of ScienceCairo University12613 GizaEgypt

In characterizing the chiral phase-structure of pseudoscalar(J^(pc) = 0^(-+)), scalar(J^(pc) = 0^(++)), vector(J^(pc) =1^(--)) and axial-vector(J^(pc) = 1^(++)t) meson states and their dependence on temperature, chemical potential, and magnetic field,we utilize the SU(3) Polyakov linear-sigma model(PLSM) in the mean-field approximation. We first determine the chiral(non)strange quark condensates,σ_l and σ_s, and the corresponding deconfinement order parameters, φ and φ~*, in thermal and dense(finite chemical potential) medium and finite magnetic field. The temperature and the chemical potential characteristics of nonet meson states normalized to the lowest bosonic Matsubara frequency are analyzed. We note that all normalized meson masses become temperature independent at different critical temperatures. We observe that the chiral and deconfinement phase transitions are shifted to lower quasicritical temperatures with increasing chemical potential and magnetic field. Thus, we conclude that the magnetic field seems to have almost the same effect as the chemical potential, especially on accelerating the phase transition, i.e. inverse magnetic catalysis. We also find that increasing the chemical potential enhances the mass degeneracy of the various meson masses, while increasing the magnetic field seems to reduce the critical chemical potential, at which the chiral phase transition takes place. Our mass spectrum calculations agree well with the recent PDG compilations and PNJL, lattice QCD calculations, and QMD/UrQMD simulations.

关键词： Chiral transition magnetic fields magnetic catalysis critical temperature viscous properties of QGP

New Progress in Helicopter Rotor Wake Research

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2019年第1期36卷 36-56页

作者： XU Guohua SHI Yongjie ZHAO Qijun National Key Laboratory of Science and Technology on Rotorcraft Aeromechanics Nanjing University of Aeronautics and Astronautics

Rotor wake analysis,a fundamental research of helicopter technology,has been widely applied for rotor aerodynamic analysis. This paper summarizes the research of different rotor wake models at home and abroad and reviews the development process of rotor wake methods as well as the research achievement obtained in each ***,the new progress of helicopter rotor wake methods is described in detail. It includes constant circulation contours modeling method of rotor wake,pseudo-implicit relaxation iteration and time-accurate solution method,research on aerodynamic interaction characteristics of helicopter rotor/fuselage by wake method,research on the rotor blade-vortex interaction noise and interaction of coaxial rigid rotor aerodynamics by viscous vortex particle method,and application of free wake method to helicopter flight dynamics modeling. In the end,some prospects for the research of helicopter rotor wake method are put forward,which clarifies the ideas for the future development of rotor wake method.

关键词： helicopter rotor free wake viscous vortex particles aerodynamic characteristics flight dynamics wake progress

Preparation of γ-Al_2O_3 composite membrane and examination of membrane defects

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 1997年第1期40卷 31-36页

作者：李安武宏宾谷景华熊国兴 State Key Laboratroy of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China

A boehmite sol with a narrow particle size distribution and most probable diameter of 35 nm was prepared by peptization of boehmite suspension with HNO3 An unsupported γ-Al2O3 membrane made from the above sol possessed a narrow pore size distribution,with an average pore size of 4.8 nm and 320 m2/g specific surface area.A supported y-Al2O3 membrane produced by repeating dipping-drying-calcination procedure twice was proven to be defect-free by gas permeation measurements and SEM.

关键词： r-AlOOH sol composite membrane integrity permeability viscous flow Knudsen flow

Numerical Analysis of Magnetohydrodynamic Navier’s Slip Visco Nanofluid Flow Induced by Rotating Disk with Heat Source/Sink

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2019年第9期71卷 1075-1083页

作者： M.Awais S.Bilal M.Y.Malik Khalil-ur-Rehman Department of Mathematics AIR UniversitySector E-9Air ComplexIslamabad44000Pakistan Department of Mathematics College of SciencesKing Khalid UniversityAbha61413Saudi Arabia Department of Mathematics Quaid-i-Azam UniversityIslamabad44000Pakistan

Current exertion is made to depict and search out the flow features imparted to viscid fluid flow over a rotational disk. Impression of magnetic field with rotating fluid is generated by interacting it in radial *** structured particles with magnetized fluid are also incorporated in the upshot of chemical reaction and absorptive/generative heat induction. Von Kumaran procedure is executed to obtain flow narrating differential *** pattern regarding thermal, momentum profiles are comprehended with the support of shooting method and RungeKutta methods. Furthermore, to get more realistic view of result description computational algorithm is modified by improving Runge-Kutta coefficients with Cash and Carp method. The aspects of flow controlling parameters like momentum slip parameter, magnetic strength parameter, Brownian motion parameter, thermophoresis parameter are adorned in sketches. Findings of these architects are accumulated in conclusion section.

关键词： heat generation/absorption viscous fluid model nanoparticles rotating disk Navier slip Cash and Carp method

Numerical Simulation of Liquefaction-Induced Settlement of Existing Structures

在线全文

学校读者我要写书评

暂无评论

Journal of Earth Science 2023年第2期34卷 339-346页

作者： Wuwei Mao Wei Li Rouzbeh Rasouli Naveed Ahmad Hu Zheng Yu Huang Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji UniversityShanghai 200092China Jacobs TorontoOntario M2J 1R3Canada Department of Civil Engineering University of Engineering and TechnologyTaxila 47050Pakistan

This study presents a numerical approach for assessment of the structure settlement problems in liquefied *** fluid dynamics theory was applied to model the liquefied soils and the rigid body dynamics theory was applied to compute the structure’s translational and angular motions in six degrees of *** dynamic mesh method was applied to modify the deformed mesh due to structure *** table tests were carried out to reproduce the structure’s subsidence behavior and provide validation for the numerical *** show that the settlement of the structure occurred most rapidly at the very beginning of liquefaction,and then it decreased *** structure settlements occurred within 10 s after *** different structure weights,structure with larger weight yielded larger amount of settlement and higher peak settlement *** results obtained in this study are beneficial for assessment of structure settlement problems in liquefaction prone areas.

关键词： liquefaction computational fluid dynamics viscous dynamic mesh shaking table test engineering geology