检索结果-内蒙古大学图书馆

Emergence of rheological properties in lattice Boltzmann simulations of gyroid mesophases

EUROPHYSICS LETTERS 2006年第4期73卷 533-539页

作者： Giupponi, G Harting, J Coveney, PV UCL Dept Chem Ctr Computat Sci London WC1H 0AJ England Univ Stuttgart Inst Computat Phys D-70569 Stuttgart Germany

We use a lattice Boltzmann (LB) kinetic scheme for modelling amphiphilic fluids that correctly predicts rheological effects in flow. No macroscopic parameters are included in the model. Instead, three-dimensional hydrodynamic and rheological effects are emergent from the underlying particulate conservation laws and interactions. We report evidence of shear thinning and viscoelastic flow for a self-assembled gyroid mesophase. This purely kinetic approach is of general importance for the modelling and simulation of complex fluid flows in situations when rheological properties cannot be predicted a priori.

关键词： computational methods in fluid dynamics Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems (hydrophilic and hydrophobic interactions) Rheology: Material behaviour

来源：评论

学校读者我要写书评

暂无评论

Grad's approximation for missing data in lattice Boltzmann simulations

引用

EUROPHYSICS LETTERS 2006年第2期74卷 215-221页

作者： Chikatamarla, SS Ansumali, S Karlin, IV ETH Aerothermochem & Combust Syst Lab CH-8092 Zurich Switzerland Nanyang Technol Univ Sch Chem & Biomed Engn Singapore 639798 Singapore

Engineering applications of computational fluid dynamics typically require specification of the boundary conditions at the inlet and at the outlet. It is known that the accuracy and stability of simulations is greatly influenced by the boundary conditions even at moderate Reynolds numbers. In this paper, we derive a new outflow boundary condition for the lattice Boltzmann simulations from non-equilibrium thermodynamics and Grad's moment closure. The proposed boundary condition is validated with a three-dimensional simulation of a backward facing step flow. Results demonstrate that the new outlet condition significantly extends the simulation capability of the lattice Boltzmann method.

关键词： Kinetic theory computational methods in fluid dynamics

来源：评论

学校读者我要写书评

暂无评论

Finite-difference lattice Boltzmann approach to pressure-driven microchannel flow with variable temperature

引用

EUROPHYSICS LETTERS 2006年第5期76卷 829-835页

作者： Sofonea, V. Romanian Acad Ctr Fundamental & Adv Tech Res RO-300223 Timisoara Romania

Diffuse reflection boundary conditions are introduced in a two-dimensional thermal lattice Boltzmann model to allow for variable fluid density along the walls. The capability of this model to capture the main characteristics of pressure-driven flow in microchannels (temperature drop, rarefaction effects, velocity slip and the minimum of the flow rate as a function of the Knudsen number) is checked.

关键词： Rarefied gas dynamics computational methods in fluid dynamics Hydrodynamics in specific geometries, flow in narrow channels

来源：评论

学校读者我要写书评

暂无评论

Lattice Boltzmann simulations of apparent slip in hydrophobic microchannels

引用

EUROPHYSICS LETTERS 2006年第2期75卷 328-334页

作者： Harting, J. Kunert, C. Herrmann, H. J. Univ Stuttgart Inst Computat Phys D-70569 Stuttgart Germany

Various experiments have found a boundaryslip in hydrophobic microchannel flows, but a consistent understanding of the results is still lacking. While Molecular dynamics ( MD) simulations cannot reach the low shear rates and large system sizes of the experiments, it is often impossible to resolve the needed details with macroscopic approaches. We model the interaction between hydrophobic channel walls and a fluid by means of a multi-phase lattice Boltzmann model. Our mesoscopic approach overcomes the limitations of MD simulations and can reach the small flow velocities of known experiments. We reproduce results from experiments at small Knudsen numbers and other simulations, namelyan increase of slip with increasing liquid-solid interactions, the slip being independent of the. ow velocity, and a decreasing slip with increasing bulk pressure. Within our model we develop a semi-analytic approximation of the dependence of the slip on the pressure.

关键词： Wall slip and apparent slip Liquid-solid interfaces computational methods in fluid dynamics

来源：评论

学校读者我要写书评

暂无评论

General characteristic-based algorithm for off-lattice Boltzmann simulations

引用

EUROPHYSICS LETTERS 2006年第3期75卷 434-440页

作者： Bardow, A. Karlin, I. V. Gusev, A. A. ETH Dept Mat Inst Polymers CH-8093 Zurich Switzerland ETH Dept Mech & Proc Engn Inst Energy Technol CH-8092 Zurich Switzerland

The Lattice Boltzmann method offers an appealing potential for simulation of fluid flows. However, the intrinsic coupling of momentum and space discretization restricts the applicability of the traditional Lattice Boltzmann method to uniform, regular lattices which is often disadvantageous in practice. Available off-lattice Boltzmann algorithms have stability problems which are to be handled at the expense of additional computational cost. Here, we propose and validate a general characteristic-based algorithm for off-lattice Boltzmann simulations that preserves all appealing properties of the standard Lattice Boltzmann method while extending the method to unstructured grids. Both, finite-element and finite-difference implementations of the algorithms are exemplified.

关键词： computational methods in fluid dynamics Kinetic theory

来源：评论

学校读者我要写书评

暂无评论

On the use of lattice Fokker-Planck models for hydrodynamics

引用

EUROPHYSICS LETTERS 2006年第3期75卷 399-405页

作者： Moroni, D. Hansen, J. -P. Melchionna, S. Succi, S. Univ Cambridge Dept Chem Cambridge CB2 1EW England Univ Roma La Sapienza Dipartimento Fis INFM SOFT I-00185 Rome Italy CNR Ist Applicaz Calcolo A Picone I-00161 Rome Italy

A recently proposed numerical scheme to solve the Fokker-Planck equation within the lattice Boltzmann framework is adapted to solve the equations of hydrodynamics. The scheme is discussed, tested on cavity flow simula... 详细信息

关键词： Kinetic theory computational methods in fluid dynamics

来源：评论

学校读者我要写书评

暂无评论

fluid-structure interaction in a free end textile vascular prosthesis

引用

EUROPEAN PHYSICAL JOURNAL-APPLIED PHYSICS 2005年第3期31卷 211-216页

作者： Ben Abdessalem, S Durand, B Akesbi, S Chakfe, N Kretz, JG ISET Ksar Hellal Text Res Unit Ksar Hellal 5070 Tunisia Ecole Natl Super Ind Text Mulhouse Lab Phys Mecan Text Mulhouse France Hop Univ Strasbourg Dept Cardiovasc Surg Strasbourg France

Textile cardiovascular prostheses are tubular structures made of polyester. laments. They present particular mechanical properties linked to wavy form of their walls allowing them to stretch under pressure. Pulsatile blood flow was studied in a moving walls vascular prosthesis. First, an image processing device was used to measure prosthesis displacement under air pressure in an free end impregnated tex-textile prosthesis. Then, fluid-structure interaction is simulated with a numerical computation code allowing tile to couple prosthesis walls motion with blood flow. Navier-Stokes equations governing fluid flow are nu-numerically solved with N3S code based on finite elements method. The numerical process is based on the Arbitrary Lagrangian Eulerian ( ALE) formulation allowing moving domains. The obtained results showed a particular distribution of blood flow velocities and shear stress near the graft walls. The flow velocity distribution near a prosthetic surface is strongly influenced by the crimping morphology and deformation. A local flow analysis is imperative to understanding pathologies implying hemodynamic factors and to optimize the prosthesis design.

关键词： computational methods in fluid dynamics Rheology of body fluids

来源：评论

学校读者我要写书评

暂无评论

A problem-orientable numerical algorithm for modeling multi-dimensional radiative MHD flows in astrophysics - the hierarchical solution scenario

引用

COMPUTER PHYSICS COMMUNICATIONS 2005年第1期168卷 1-24页

作者： Hujeirat, A Heidelberg Univ Inst Appl Math D-69120 Heidelberg Germany

We present a hierarchical algorithm for the adaptation of numerical solvers in high energy astrophysics. This approach is based on clustering the entries of the global Jacobian in a hierarchical manner that enables employing a variety of solution procedures ranging from a purely explicit time-stepping up to fully implicit schemes. A gradual coupling of the radiative MHD equation with the radiative transfer equation in higher dimensions is possible. Using this approach, it is possible to follow the evolution of strongly time-dependent flows with low/high accuracies and with efficiency comparable to explicit methods, as well as searching quasi-stationary solutions for highly viscous flows. In particular, it is shown that the hierarchical approach is capable of modeling the formation of jets in active galactic nuclei and reproduce the corresponding spectral energy distribution with a reasonable accuracy. (c) 2005 Elsevier B.V. All rights reserved.

关键词： computational methods in fluid dynamics radiation transfer magnetohydrodynamics physical processes

来源：评论

学校读者我要写书评

暂无评论

A reduced-order model for a bubbling fluidized bed based on proper orthogonal decomposition

引用

COMPUTERS & CHEMICAL ENGINEERING 2005年第2期30卷 243-259页

作者： Yuan, T Cizmas, PG O'Brien, T Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA Dept Energy Natl Energy Technol Lab Morgantown WV 26507 USA

This paper presents the development of a reduced-order model (ROM) for dynamics of non-reactive, isothermal fluidized beds, based on the proper orthogonal decomposition (POD) method. Several implementations of this ROM were developed for a two-dimensional bubbling fluidized bed using numerical results from a full computational fluid dynamics (CFD) simulation of the bed. The solutions of the ROM were used to investigate the influence of the size of the particles on the motion of the bed. The solutions of the ROM were compared with the full model solutions for different particle diameters. The differences between the ROM and the full order solutions (the CFD results) were less than 3% within the range of diameters used for POD generation. The computational time of the ROM varied between 25 and 33% of the computational time of the full CFD solution. The computational speed-up depended on the complexity of the transport phenomena, the ROM methodology and the reconstruction error. (c) 2005 Elsevier Ltd. All right reserved.

关键词： computational methods in fluid dynamics multiphase flow nonlinear dynamics

来源：评论

学校读者我要写书评

暂无评论

Fluctuations and continuity in particle-continuum hybrid simulations of unsteady flows based on flux-exchange

引用

EUROPHYSICS LETTERS 2005年第6期69卷 959-965页

作者： Delgado-Buscalioni, R Flekkoy, EG Coveney, PV UCL Dept Chem Ctr Computat Sci London WC1H 0AJ England Univ Nacl Educ Distancia Dept Ciencias & Tecnicas Fisicoquim Fac Ciencias Madrid 28040 Spain Univ Oslo Dept Phys N-0316 Oslo Norway

This letter describes the treatment of unsteady liquid flow by a hybrid particle-continuum scheme. The scheme couples a particle region described by molecular dynamics with a coarse-grained domain solved by continuum fluid dynamics. The particle and continuum domains overlap in the coupling region, where two-way transfer of momentum flux is established. We demonstrate that this flux-coupling scheme is able to describe high-frequency oscillatory flows and to ensure the continuity of velocity across the particle-continuum interface. The effect of fluctuations within the particle system is also analysed and establishes the range in frequency and flow wave number for which hydrodynamic fluctuations need to be taken into account within the continuum description.

关键词： computational methods in fluid dynamics Molecular dynamics and particle methods fluidics

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：