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Communications in Computational Physics 2010年第9期8卷 877-900页

作者： A.Burbeau-Augoula CEA DIFF-91297 ArpajonFrance

This work deals with the simulation of two-dimensional Lagrangian hydrodynamics problems.Our objective is the development of an artificial viscosity that is to be used in conjunction with a staggered placement of variables:thermodynamics variables are centered within cells and position and fluid velocity at vertices.In[J.Comput.Phys.,228(2009),2391-2425],Maire develops a high-order cell-centered scheme for solving the gas dynamics equations.The numerical results show the accuracy and the robustness of the method,and the fact that very few Hourglass-type deformations are present.Our objective is to establish the link between the scheme of Maire and the introduction of artificial viscosity in a Lagrangian code based on a staggered grid.Our idea is to add an extra degree of freedom to the numerical scheme,which is an approximation of the fluid velocity within cells.Doing that,we can locally come down to a cell-centered approximation and define the Riemann problem associated to discrete variable discontinuities in a very natural way.This results in a node-centered artificial viscosity formulation.Numerical experiments show the robustness and the accuracy of the method,which is very easy to implement.

关键词： hydrodynamics staggered discretization artificial viscosity Lagrangian simulation shock waves finite volume scheme

Shafting Alignment Based on hydrodynamics Simulation Under Larger Rudder Corner Conditions

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Journal of Shanghai Jiaotong university(Science) 2012年第4期17卷 427-435页

作者：杨勇马捷唐文勇车驰东张桂臣 State Key Laboratory of Ocean Engineering Shanghai Jiaotong University

With the rudder angles getting larger and larger,the moment and force on propeller shafts,which are caused by complex flowing field,become more and more.They influence the shafting alignment greatly.Stress analysis of propeller shafts has been done under increasing rudder corner conditions with complex hydrodynamics simulation for a great domestic liquified natural gas(LNG) vessel,which is with dual propulsion systems.The improved three-moment equation is adopted in the process of dual propulsive shafting alignment.The calculated results show that the propeller hydrodynamic characteristics,which affect dual propulsive shafting alignment greatly,must be considered under large rudder angle conditions.Shafting accidents of Korean LNG vessels are interpreted reasonably.At the same time,salutary lessons and references are afforded to the marine multi-propulsion shafting alignment in the future.

关键词： shafting alignment improved three-moment equation flowing field simulation hydrodynamics rudder corner multi-propulsion system

Monolithic Coupling of the Pressure and Rigid Body Motion Equations in Computational Marine hydrodynamics

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Journal of Marine Science and Application 2017年第4期16卷 375-381页

作者： Hrvoje Jasak Inno Gatin Vuko Vukcevic Faculty of Mechanical Engineering and Naval Architecture University of Zagreb 10000 Zagreb Croatia

In Fluid Structure Interaction(FSI) problems encountered in marine hydrodynamics, the pressure field and the velocity of the rigid body are tightly coupled. This coupling is traditionally resolved in a partitioned manner by solving the rigid body motion equations once per nonlinear correction loop, updating the position of the body and solving the fluid flow equations in the new configuration. The partitioned approach requires a large number of nonlinear iteration loops per time–step. In order to enhance the coupling, a monolithic approach is proposed in Finite Volume(FV) framework,where the pressure equation and the rigid body motion equations are solved in a single linear system. The coupling is resolved by solving the rigid body motion equations once per linear solver iteration of the pressure equation, where updated pressure field is used to calculate new forces acting on the body, and by introducing the updated rigid body boundary velocity in to the pressure equation. In this paper the monolithic coupling is validated on a simple 2D heave decay case. Additionally, the method is compared to the traditional partitioned approach(i.e. "strongly coupled" approach) in terms of computational efficiency and accuracy. The comparison is performed on a seakeeping case in regular head waves, and it shows that the monolithic approach achieves similar accuracy with fewer nonlinear correctors per time–step. Hence, significant savings in computational time can be achieved while retaining the same level of accuracy.

关键词： monolithic coupling pressure equation rigid body motion computational fluid dynamics marine hydrodynamics seakeeping

Derivation of hydrodynamics for Multi-Relaxation Time Lattice Boltzmann using the Moment Approach

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Communications in Computational Physics 2013年第3期13卷 614-628页

作者： Goetz Kaehler Alexander J.Wagner Department of Physics North Dakota State UniversityFargoND 58105USA

A general analysis of the hydrodynamic limit of multi-relaxation time lattice Boltzmann models is presented.We examine multi-relaxation time BGK collision operators that are constructed similarly to those for the MRT case,however,without explicitly moving into a moment space representation.The corresponding’moments’are derived as left eigenvectors of said collision operator in velocity space.Consequently we can,in a representation independent of the chosen base velocity set,generate the conservation equations.We find a significant degree of freedom in the choice of the collision matrix and the associated basis which leaves the collision operator invariant.We explain why MRT implementations in the literature reproduce identical hydrodynamics despite being based on different orthogonalization relations.More importantly,however,we outline a minimal set of requirements on the moment base necessary to maintain the validity of the hydrodynamic equations.This is particularly useful in the context of position and time-dependent moments such as those used in the context of peculiar velocities and some implementations of fluctuations in a lattice-Boltzmann simulation.

关键词： Lattice Boltzmann kinetic theory Navier-Stokes hydrodynamics

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Editorial Message

Journal of hydrodynamics 2019年第2期31卷 428-428页

作者： Editorial office of Journal of hydrodynamics 不详

Dear Ladies and Gentlemen,Springer will start publishing Journal of hydrodynamics(ISSN 1001-605&e-ISSN 1878-0342)from 2018 onwards.The editorial system is the Editorial Manager(EM)via http://***/IJHD For updated infor... 详细信息

关键词： Editorial Message hydrodynamics Editorial Manager(EM)

RESEARCH AND PROGRESS OF WEISFOGH MECHANISM hydrodynamics

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Journal of hydrodynamics 1999年第3期11卷 55-60页

作者： Zhang She sheng, Wu Xiu heng, Wan Xian fu Department of Mathematics, Wuhan Transportation Univercity, Wuhan 430063, P.R.China (Received Sep. 28, 1998)

Attention is focused on the research and progress of Weis Fogh mechanism hydrodynamics in this paper. We review some physical models and mathematical models of Weis Fogh mechanism, and also describe some analytic me... 详细信息

关键词： Weis Fogh mechanism hydrodynamics mathematical model

Recent advances in wave energy converters based on nonlinear stiffness mechanisms

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 1081-1108页

作者： Xiantao ZHANG Haicheng ZHANG Xiao ZHOU Ze SUN State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China China Ship Scientific Research Center Wuxi 214082Jiangsu ProvinceChina

Wave energy is one of the most abundant renewable clean energy sources,and has been widely studied because of its advantages of continuity and low seasonal variation.However,its low capture efficiency and narrow capture frequency bandwidth are still technical bottlenecks that restrict the commercial application of wave energy converters(WECs).In recent years,using a nonlinear stiffness mechanism(NSM)for passive control has provided a new way to solve these technical bottlenecks.This literature review focuses on the research performed on the use of nonlinear mechanisms in wave energy device utilization,including the conceptual design of a mechanism,hydrodynamic models,dynamic characteristics,response mechanisms,and some examples of experimental verification.Finally,future research directions are discussed and recommended.

关键词： wave energy efficiency nonlinear stiffness hydrodynamics bistable

Hydrodynamic performances and wakes induced by a generic submarine operating near the free surface in continuously stratified fluid

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水动力学研究与进展B辑:英文版 2023年第3期35卷 396-406页

作者： Liu-shuai Cao Gang Gao En-kai Guo De-cheng Wan School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The wake of a submarine is a crucial element that greatly affects its stealth and hydrodynamic performance.To investigate the propagation and evolution characteristics of submarine wakes in a stratified fluid,particularly under free surface conditions,a numerical method to simulate the linearly stratified environment was developed.A thermocline model based on Boussinesq assumption was introduced to match the continuously stratified fluid.The volume of fluid(VOF)method was utilized to capture free surface waves,while a fully structured grid and the SST k-ωturbulence model were combined to solve the complex flow of submarines.Grid independence study in homogenous flow near the free surface was initially conducted.Furthermore,the hydrodynamic performance,wake evolution characteristics,free surface signatures as well as decay of velocity under different stratification levels were analyzed.Results demonstrated that the numerical method employed was efficient in simulating stratified flows.Moreover,it showed that density stratification had a significant impact on the hydrodynamics and wake characteristics of a submarine,especially under strong density stratification circumstances.

关键词： Wakes submarine free surface stratified fluid hydrodynamics

The dynamics of river confluences and their effects on the ecology of aquatic environment:A review

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Journal of hydrodynamics 2022年第1期34卷 1-14页

作者： Sai-yu Yuan Lei Xu Hong-wu Tang Yang Xiao Carlo Gualtieri State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing210024China Yangtze Institute for Conservation and Development Nanjing210024China Department of Structures for Engineering and Architecture University of Napoli Federico IINapoliItaly

Confluences act as critical nodes in a river system.They affect hydrodynamics,sediment transport,bed morphology,and eco-hydraulics of the river system.Convergence of streams produces the complex mechanism of flow momentum and mass mixing which may affect the aquatic environment locally and even lasting for a long distance downstream.The confluence creates a hotspot for the river system’s ecological change,which usually leads to changes in water temperature,suspended-sediment load,bed material,nutrient concentrations,water chemistry,and organic-matter content.Hence,the dynamics of river confluences are very complex and have critical effects on river system’s water environment and ecology.For this reason,a review summarizing turbulent flow,sediment transport,morphological-dynamics,mixing processes,and their effects on the ecology of the aquatic environment at river confluences is in order.A future research agenda and opportunities pertinent to river confluence are vitally emphasized as a multidisciplinary research topic.

关键词： River confluence hydrodynamics sediment transport morpho dynamics water environment water ecology

Impacts of solid physical properties on the performances of a slurry external airlift loop reactor integrating mixing and separation

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Chinese Journal of Chemical Engineering 2023年第3期55卷 1-12页

作者： Tian Zhang Qingshan Huang Shujun Geng Aqiang Chen Yan Liu Haidong Zhang School of Chemical Engineering Hebei University of TechnologyTianjin 300130China Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)Chinese Academy of Sciences(CAS)Qingdao 266101China Dalian National Laboratory for Clean Energy(DNL) Dalian 116023China Innovation Academy for Green Manufacture Institute of Process EngineeringCASBeijing 100190China Synthetic Biology Technology Innovation Center of Shandong Province Qingdao 266101China Shandong Energy Institute Qingdao 266101China

Solid physical properties are vital for the design, optimization, and scale-up of gas–liquid–solid multiphase reactors. The complex and interactional effects of the solid physical properties, including particle diameter, density, wettability, and sphericity, on the hydrodynamic behaviors in a new external airlift loop reactor(EALR) integrating mixing and separation are decoupled in this work. Two semi-empirical equations are proposed and validated to predict the overall gas holdup and liquid circulating velocity satisfactorily, and then the individual influence of such solid physical properties is further investigated. The results demonstrate that both the overall gas holdup in the riser and the liquid circulating velocity in the downcomer increase with the contact angle, but decrease with particle size, density, and sphericity.Additionally, the impact of the particle size on the liquid circulating velocity is also profoundly revealed on a micro-level considering the particle size distribution. Moreover, the axial solid concentration distribution is discussed, and the uniformity of the slurry is described by the mixing index of the solid particles. The results show that a more homogeneous mixture can be achieved by adding finer particles other than attaining violent turbulence. Therefore, this work lays a foundation for the design, scale-up, and industrialization of the EALRs.

关键词： Slurry reactor hydrodynamics Particle Mixing Solid physical property