Measurement and Analysis of Natural-Type Surface Roughnesses Affecting Fluid Flow.

摘要

An investigation is reported of the feasibility of using the statistical distributions of roughness heights,slopes,and curvatures to characterize hydraulically rough surfaces. The direct measurement technique,such as has been employed to find the root-mean-square value of roughness heights,is evaluated. When automatically measured and recorded profiles of developing sand bed roughness became available,it was found that each distribution approaches a well defined limit,suggesting that 95percentile values may be used to characterize natural-type roughnesses.