The Experts below are selected from a list of 37527 Experts worldwide ranked by ideXlab platform
Zhuoqing An - One of the best experts on this subject based on the ideXlab platform.
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correlating the apparent viscosity with gas solid Suspension Flow in straight pipelines
Powder Technology, 2019Co-Authors: Zhuoqing AnAbstract:Abstract The apparent viscosity of dilute solids Suspension Flows has been inferred from the experimentally measured frictional pressure drop in a specially designed downFlow straight pipeline. The results indicate that the apparent viscosity of gas-solid Suspension Flow increases with the increment of the solids holdup, and is, in the transition region only, inversely proportional to the gas velocity. As the influence of gas velocity to the gas-solid Suspension Flow becomes negligible in the turbulent region, the apparent viscosity can be linearly correlated with the solids holdup. New correlations for the apparent viscosity of the gas-solid Suspension Flow in straight pipelines were proposed.
Akihiko Shimizu - One of the best experts on this subject based on the ideXlab platform.
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Numerical Simulation of Turbulent Gas-Solid Suspension Flow by L、arge Eddy Simulation
Engineering sciences reports Kyushu University, 2000Co-Authors: Takehiko Yokomine, Takuya Tsuji, Akihiko ShimizuAbstract:Aparticle-laden channel Flow has been simulated by a large eddy simulation, which is expected to have asubstitutability for DNS in order to makeん一emodel for Suspension Flow minute. The numerical results for the fluid turbulence modulation due to particles are strongly depends on how exact the particle motion is described, especially particle/wall interaction and interparticle collision. In addition to that, it is necessary to modify the sub-grid scale(SGS)turbulence model to take the interaction between particle and small scale turbulence into account. The effort of modification of SGS scale model, however, might cause the same difficulties as the Suspension 1ヒーemodel development. This paper proposes LES model for the gas-solid Suspension Flow by using Localized DynamicんsGs Equation Model, which can determine model constants dynamically and has possibility of considering back-scatter energy transfer including particulate medium. The proposed model is applied to prediction of a channel Flow experiment by Kulick et al.
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Experimental investigation on impingement heat transfer of gas-solid Suspension Flow
1999Co-Authors: Takenhiko Yokomine, Akihiko ShimizuAbstract:This paper aims to demonstrate experimentally the heat transfer performance of dense gas-solid Suspension impinging jet for diverter cooling of the fusion power reactor. Prior to the experimental study, a tentative goal of 20 kW/m{sup 2}K was set as the heat transfer coefficient based on the expected temperature level of both coolant and diverter plate materials. Figure A-1 summarizes the results of experiments, where H/D is non-dimensional space between nozzle exit and impingement plate. The ranges of examined nozzle Reynolds number Re{sub N} and thermal loading ratio {Gamma}{sub th} were 5.5 x 10{sup 4} {
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Numerical prediction of erosion for Suspension Flow duct
Wear, 1995Co-Authors: Seiichi Sato, Akihiko Shimizu, Takehiko YokomineAbstract:An attempt was made to predict numerically the erosion rate of wall surfaces of a gas-solid Suspension Flow duct in order to establish a prediction method with wide applicability. First, the erosion rate due to a single particle collision was quantified using equations by Finnie and Bitter. The empirical constants for these equations were determined experimentally. Then, the expressions obtained were incorporated into a mathematical model based on the Eulerian description for the continuous phase as well as on the Lagrangian description for the particulate phase. In order to demonstrate the prediction accuracy, an attempt was made to reproduce the actual erosion rate observed on the surfaces of a square cross-sectioned L-type Suspension Flow duct. Fairy good agreement was obtained between the prediction and the measurement.
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erosion of the target surface due to vertical impingement of a gas solid Suspension jet
Fusion Engineering and Design, 1992Co-Authors: Akihiko Shimizu, Shu HasegawaAbstract:Abstract The possibility of a fusion reactor blanket concept in which gas-solid Suspension Flows are used as coolant, depends crucially on the degree of erosion of the walls of the coolant channels. This paper presents an experimental study on the erosion of a stainless steel target surface on which a gas-solid Suspension Flow impinges vertically. Vertical impingement of the Suspension Flow is considered to be a promising Flow configuration for first-wall cooling. Three kinds of material (glass beads, alumina and graphite) were used as the suspended particles and the effects of each of the Flow parameters are examined separately. Based on the experimental results, the erosion depth per year is estimated for several conditions and discussions are presented on the selection of the advisable Flow conditions that lead to minimize the erosion.
J. S. Marshall - One of the best experts on this subject based on the ideXlab platform.
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Aggregate growth and breakup in particulate Suspension Flow through a micro-nozzle
Microfluidics and Nanofluidics, 2010Co-Authors: J. A. Mousel, J. S. MarshallAbstract:A computational study is reported on the growth of aggregates in Flow of a particulate Suspension through a micro-nozzle. The study employs a soft-sphere discrete element method (DEM) with van der Waals adhesion force between the particles in two-dimensional, incompressible channel Flow. A new computational approach for particle transport in complex domains is developed which uses a background Cartesian grid for efficient Flow field interpolation at the particle locations, together with a level-set method to represent the nozzle boundaries in the particle computation. Three mechanisms for the growth or breakup of particulate aggregates in the micro-nozzle are examined: (1) enhanced particle collision due to lateral compression as fluid elements pass through the nozzle, (2) stretching of aggregates due to axial stretching of fluid elements, and (3) collision and intermittent adhesion of particles to the nozzle wall. The first of these mechanisms leads to aggregate growth, and the second to aggregate breakup. The wall collision and adhesion mechanism can enhance either aggregate growth or breakup, but it is found in most cases to be a primary agent in the breakup of incident aggregates as part of the aggregate attaches to the nozzle wall and is torn from the remainder of the aggregate due to the high shear near the walls. Simplified models for these processes are developed and used to interpret the trends observed in the DEM simulations. The effects of particle adhesion parameter, particle size and density, particle concentration, and nozzle geometry are examined. It is found that passage of a particulate Suspension through a nozzle can lead to either a substantial decrease in aggregate size or a modest increase under different conditions, depending in part on the size of the incident aggregates.
David Hurther - One of the best experts on this subject based on the ideXlab platform.
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Turbulent particle and momentum flux statistics in Suspension Flow
Water Resources Research, 2003Co-Authors: David Hurther, Ulrich LemminAbstract:The particle entrainment ability of coherent Flow structures is investigated by comparing statistical properties of momentum flux u′w′ and of turbulent mass fluxes c′u′ and c′w′ in Suspension, open‐channel Flow under capacity charge conditions. The quadrant repartitions of these quantities as a function of the corresponding threshold levels are estimated. A cumulant discard probability density distribution is used to calculate the theoretical quadrant dynamics. Good agreement between the third‐order model and the experimental results is found for all investigated quantities in the wall and intermediate Flow regions. In the free surface domain, the increase of intermittency of the momentum and mass transport processes leads to small discrepancies between the model and the experimental results. The quadrant distributions of the horizontal and vertical turbulent mass fluxes are dominated by the same two quadrants as the momentum flux u′w′. Ascendent mass flux events are found to correlate with ejections over the entire water depth. A dynamical equilibrium between the shear stress production term and the turbulent energy dissipation term is found in the intermediate Flow region where the value of the normalized vertical flux of turbulent kinetic energy in Suspension Flow corresponds well with the one observed in clear water Flows. This points toward a universality of the normalized vertical flux of turbulent kinetic in highly turbulent boundary layers. The suspended particle transport capacity of coherent structures is directly quantified from the estimation of the conditionally sampled terms of the particle diffusion equation. Coherent structures are found to play a dominant role in the mass transport mechanism under highly turbulent Flow conditions in open‐channel Flows.
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Sediment transport assessment in Suspension Flow based on coherent structures characteristics
2001Co-Authors: David HurtherAbstract:The sediment entrainment ability of coherent Flow structures is investigated by comparing higher order statistical properties of shear stress and of turbulent mass fluxes in Suspension, open-channel Flow under capacity charge conditions. The quadrant repartitions of these quantities as a function of the corresponding threshold levels are estimated using a higher order cumulant discarded probability density distribution of the time fluctuating velocity and concentration fields. Good agreement between the third order model and the experimental results is found for all investigated quantities in the wall and intermediate Flow regions. The quadrant distributions of the relative horizontal and vertical mass fluxes are dominated by the same two quadrants as the shear stress. The suspended sediment transport capacity of coherent structures is directly quantified from the estimation of the conditionally sampled terms of the sediment diffusion equation. Coherent structures of a burst cycle are found to be important contributors in the mass transport mechanism under highly turbulent Flow conditions in open-channel Flows. Direct estimation of the time scales of coherent structures permitted to correct a novel formulation of the near bed equilibrium concentration proposed recently by Cao (1999).
U Tuzun - One of the best experts on this subject based on the ideXlab platform.
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explicit numerical simulation of Suspension Flow with deposition in porous media influence of local Flow field variation on deposition processes predicted by trajectory methods
Chemical Engineering Science, 2003Co-Authors: Mark J Biggs, S J Humby, A Buts, U TuzunAbstract:Abstract A new explicit numerical simulation (ENS) method based on lattice-gas automata (LGA) is introduced here for the Flow of solid/fluid Suspensions with deposition in porous media. The ENS method explicitly resolves the dynamics of the individual solid particles and the suspending fluid in the domain defined by the pore walls and solid particle surfaces. After describing the new method, it is applied to the study of solid/fluid Suspension Flow with deposition in a constriction and in a model random porous solid. This study clearly demonstrates that the deposits strongly influence the local Flow fields, which in turn affect the deposition process indicating that this interplay should be modelled if accurate results are desired from trajectory methods.
