SPH method for two-fluid modeling of particle-fluid fluidization

In this paper a smoothed particle hydrodynamics (SPH) method is proposed for solving the two-fluid model of dense particle-fluid fluidizations. The particle-fluid two-phase flow fields are represented with two types of SPH particles, where the interactions between particles of the same type constitute the inner-phase stress while those between particles of different types result in the drag force. Two typical fluidization systems, namely the liquid-solid sedimentation and single-orifice gas-solid bubbling fluidization, are simulated with this approach, showing good agreement with experimental data. (C) 2011 Elsevier Ltd. All rights reserved

Direct numerical simulation of particle-fluid systems by combining time-driven hard-sphere model and lattice Boltzmann method

A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM). Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems. (C) 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved

Direct numerical simulation of particle-fluid systems by combining time-driven hard-sphere model and lattice Boltzmann method

A coupled numerical method for the direct numerical simulation of particle–fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM). Particle–fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle–fluid systems

Direct numerical simulation of particle clustering in gas-solid flow with a macro-scale particle method

Particle clustering has long been a focus in the study of gas-solid flow. Detailed flow field information below the particle scale is required to understand the mechanism of its formation and the statistical properties of its dynamic behavior, but is not easily obtained in both experiments and numerical simulations. In this article, a meshless method is used to reveal such details in the destabilizing of a suspension with hundreds of particles. During the process, doublets, quadruplet and larger clusters are seen to form and disintegrate dynamically, showing a tendency to minimize local voidages. At the same time, single vertical streams, pairs of parallel streams and many irregular streams appear and disappear between particle clusters alternatively, exhibiting a tendency to suffer lowest resistance. Globally, the spatio-temporal compromise between these two tendencies results in a configuration of large clusters separated by fast flow streams. In the Clustering process, the inter-phase slip velocity is seen to increase long after the forces on each phase have stabilized, suggesting that inter-phase friction is not a function of local voidage and Reynolds number only, as commonly considered. The article concludes with prospects on the sub-grid scale models for continuum description of gas-solid flow that can be established upon such simulation results. (c) 2008 Elsevier Ltd. All rights reserved

concurrently delivering and retrieving multicast data in parallel channels for mobile users

Wuhan University, China; Dalian University of Technology, China; IEEE Antennas and Propagation Society; Scientific Research Publishing, USA; IEEE Communications SocietyNowadays, the backbone network is capable of delivering countless information at extremely high performance and high throughput. However, the abundant information in the backbone may not be retrieved by the mobile users fingertips. This paper developed t

Chem. Eng. Sci.

Due to significant multi-scale heterogeneity, understanding sub-grid structures is critical to effective continuum-based description of gassolid flow. However, it is challenging for both physical measurements and numerical simulations. In this article, with the macro-scale pseudo-particle method (MaPPM) implemented on a GPU-based HPC system, up to 30,000 fluidized solids are simulated using the NS equation directly. The destabilization of uniform suspensions and the formation of solids clusters are reproduced in two-dimensional suspensions. Distinct scale-dependence of the statistical properties in the systems at moderate solid/gas density ratio is observed. Obvious cluster formation and its effect on drag coefficient are shown in a system at high solid/gas density ratio. On the computational side, about 19 folds speedup is obtained on one GT200 GPU, as compared to a mainstream CPU core. The necessity for investigating even larger systems is prospected. (C) 2010 Elsevier Ltd. All rights reserved.Due to significant multi-scale heterogeneity, understanding sub-grid structures is critical to effective continuum-based description of gassolid flow. However, it is challenging for both physical measurements and numerical simulations. In this article, with the macro-scale pseudo-particle method (MaPPM) implemented on a GPU-based HPC system, up to 30,000 fluidized solids are simulated using the NS equation directly. The destabilization of uniform suspensions and the formation of solids clusters are reproduced in two-dimensional suspensions. Distinct scale-dependence of the statistical properties in the systems at moderate solid/gas density ratio is observed. Obvious cluster formation and its effect on drag coefficient are shown in a system at high solid/gas density ratio. On the computational side, about 19 folds speedup is obtained on one GT200 GPU, as compared to a mainstream CPU core. The necessity for investigating even larger systems is prospected. (C) 2010 Elsevier Ltd. All rights reserved

Direct numerical simulation of particle-fluid systems by combining time-driven hard-sphere model and lattice Boltzmann method

A coupled numerical method for the direct numerical simulation of particle-fluid systems is formulated and implemented, resolving an order of magnitude smaller than particle size. The particle motion is described by the time-driven hard-sphere model, while the hydrodynamic equations governing fluid flow are solved by the lattice Boltzmann method (LBM). Particle-fluid coupling is realized by an immersed boundary method (IBM), which considers the effect of boundary on surrounding fluid as a restoring force added to the governing equations of the fluid. The proposed scheme is validated in the classical flow-around-cylinder simulations, and preliminary application of this scheme to fluidization is reported, demonstrating it to be a promising computational strategy for better understanding complex behavior in particle-fluid systems. (C) 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved