2006 Fiscal Year Final Research Report Summary
Study on the 3-D Spatial Structure of Particle Cluster
| Project/Area Number |
17560149
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Osaka University |
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Principal Investigator |
TANAKA Toshitsugu Osaka University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (90171777)
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| Co-Investigator(Kenkyū-buntansha) |
TSUJI Yutaka Osaka University, Graduate School of Engineering, Professor, 大学院工学研究科, 教授 (10029233)
KAWAGUCHI Toshihiro Osaka University, Graduate School of Engineering, Research Assoc., 大学院工学研究科, 助手 (80234045)
TSUJI Takuya Osaka University, Graduate School of Engineering, Research Assoc., 大学院工学研究科, 助手 (90379123)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Multiphase Flow / Gas-Solid Flow / Particle Cluster / Spatial structure / Numerical Simulation / Experiment / Meso-Scale Structure |
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| Research Abstract |
Spatial and temporal structure of particle clusters formed in gas-solid flows is studied. Experiments are made for gravitational settling flow in a vertical duct. Spatial and temporal three-dimensional structure of particle clusters formed in the duct are reconstructed from the measured time series of high-speed camera images of particle distributions in a duct cross-section.
In addition, numerical simulations are conducted to investigate the three-dimensional spatial structure of particle clusters. The numerical simulations are made for the gas-solid flows in a rectangular-parallelepiped calculation domain surrounded by periodic boundaries. The fluid motion is calculated by using DNS, while the solid flow is calculated by using a Lagrangian model with considering the particle-particle collision. More than sixteen million particles are tracked in the maximum case.
The obtained results are summarized as follows.
(1) Three-dimensional spatial and temporal structure of particle distributions
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are obtained from the experiments. It is found that three-dimensional presentation of particle distributions enables us to find the three-dimensional nature of particle clusters.
(2) Spatial-scale characteristics of particle clusters were investigated quantitatively by analyzing the power spectrums of spatial particle concentration distributions obtained by the present simulation. The results showed that the cluster consists of multiple-spatial scales while the low wave-number, hence large-scale structure, is dominant.
(3) A reconstruction method of three-dimensional spatial structure of particle clusters based on the low-pass filtering technique in the wave-number space are proposed and applied to the flow field data obtained from the present numerical simulations. Dominant three-dimensional structures of particle cluster are successfully extracted. It becomes possible to have the detailed investigations on its three-dimensional structures and behaviors. We found that inverse U-structure which is recognizable in two-dimensional observations is a part of bent tube-like cluster elements. In three-dimensions, these cluster elements are interacting in a very complex way. Less
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