Flow in a Channel of Definite Roughness

1 January 1946

journal article
Published by American Society of Civil Engineers (ASCE) in Transactions of the American Society of Civil Engineers

Vol. 111 (1) , 531-554
https://doi.org/10.1061/taceat.0005958

Abstract

Although the effect of definite roughness of the wall upon the resistance to the flow of fluids in pipes has been thoroughly studied, there seems no equally satisfactory study of the effect of known wall roughness on the flow in open channels. This paper reports the results of some experiments bearing on this question which were performed by the writer during the summer of 1940 in the laboratory of the Institute of Hydraulic Research at Iowa City, Iowa. A total of two hundred runs on a rectangular flume, with eleven different roughnesses and four different slopes, indicated that Chézy's C could be expressed as 40 log₁₀ R/∈ + c,, in which R is the hydraulic radius, E is a measure of the roughness, and c, is a small shape correction. The mean of the deviations of the formula from the data was 2.1, and the mean percentage deviation was 4.4%.

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