| Summary: | 碩士 === 華梵大學 === 環境與防災設計學系碩士班 === 100 === Shear stress of the water mixing particles in a smooth channel bed and rough channel bed was analyzed through experimental and theoretical study in this paper. The statistical property, shch as the mean value and the coefficient of variation, for the shear stress of the water mixing particles at various particle concentrations was analyzed. The relationship of the friction coefficient (the dimensionless of the shear stress) and Reynolds number with particle concentration was also developed. Study result shows that the probability density function (PDF) of shear stress for smooth and rough beds shows normal distribution. For the average shear stress of water/particle mixture, the particle concentration is in proportion to shear stress for rough bed. The particle concentration is in reverse proportion to shear stress for rough bed. The particle concentration is in proportion to the variation coefficient of shear stress for both rough and smooth beds, but the variation coefficient is larger for smooth bed than for rough bed. On a rough bed channel, the friction coefficient for the water/particle mixture flow with low particle concentration is close to that for clear water flow; on a smooth bed channel, the friction coefficient for water/particle mixture flow is close to that for clear water flow (Blasius equation). Under the rough bed channel conditions, for clear water flow or water/particle mixing flow, the friction coefficient, f, determined in experiment is significantly different from that determined by theoretical estimation (based on the shear stress for uniform flow). Under smooth bed channel conditions, the friction coefficient, f, of clear water flow determined in experiment is closer to the f determined by theoretical estimation.
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