1990 Fiscal Year Final Research Report Summary
Development of Velocity and Density Measurement Technique for Turbulent
| Project/Area Number |
01850122
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Kobe University |
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Principal Investigator |
YANO M. Kobe Univ., Dept. Civil Engin. Ph. D. Prof., 工学部, 教授 (80031061)
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| Co-Investigator(Kenkyū-buntansha) |
MUROTA A. Osaka Industrial Univ., Dr. Eng. Prof., 工学部, 教授 (50028924)
MICHIOKU K. Kobe Univ., Dept. Civil Engin., Dr. Eng., Assoc. Prof., 工学部, 助教授 (40127303)
NAKATSUJI K. Osaka Univ., Dept. Civil Engin., Dr. Eng., Assoc. Prof., 工学部, 助教授 (10029324)
ETOH T. Kinki Univ., Dept. Civil Engin., Dr. Eng. Prof., 理工学部, 教授 (20088412)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Turbulence / Stratified Flows / Visualization / Turbulence Model / Field Measurements / Instrumentation |
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| Research Abstract |
A new technique of velocity and density measurements using a "Photon-Counting Image Detector" is developed, which could be applied to turbulence measurements in thermally stratified system. Velocity and temperature are successfully measured by counting photons in scattered light from the test section.
A method to make micro-capsules which are filled with pure water and covered with a thin film of polystyrene is developed. Their mean specific gravity is 1.0064 and mean diameter is 295 microns. This enables us to measure turbulent velocity field not only in homogeneous fluid system but also in thermally stratified system. New methods to measure three dimensional velocity profiles are also investigated. The measurement system is composed of three high-speed video camera systems, an image processing computer and an engineering work station A new algorithm for tracking tracer particles is also developed by applying Kalman's filtering theory.
Through the examination of field measurements of fl
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ow and density fields near the river mouth of Akashi River, the physical processes of gravitational spreading of river plume is discussed and the three-dimensional numerical modeling is developed. This model can be applied to Yodo River plume of maximum flow rate of 6270 m^3/s to compare with the infrared image taken by Satellite NOAA. It suggests the importance of earth's rotation effects on the large-scale river plume spreading.
A turbulence closure model is applied to simulate thermo-solutal convection in a double-diffusive stratification system. The model is capable of precisely reproducing double-diffusive mixing process ; formation of step-like density structures, merging process of neighboring two convective layers. The simulated results are compared with experiments, which shows satisfactory agreement between the analysis and the experiment. We can get information not only of mean-field but also turbulent structure. A laboratory experiment is carried out to examine turbulent velocity field produced by composite stirring. Combining these experimental and theoretical results, we could get more information on mass transport mechanism in thermally stratified closed water masses such as lakes and reservoirs.
The flow development and the entrainment process in a two-dimensional buoyant surface jet are discussed by numerical experiments using k-epsilon turbulence model and the algebraic stress model (ASM), which has been examined through the comparison with measured turbulence quantities. The ASM taking account of the damping effects of the gravitational field and the free surface is found to be in a good agreement with the empirical relationship between the entrainment rate and the Richardson number, It also shows that the dependence of entrainment rate on the Reynolds shear stress changes drastically at the shear layer Richardson number of 0.08. Its value corresponds to the critical value hitherto obtained at stratified shear flows theoretically and experimentally. Less
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Research Products
(19 results)
