WIT Press

Meandering Effect For Evaluation Of Roughness Coefficients In Open Channel Flow

Price

Free (open access)

Paper DOI

10.2495/RM110191

Pages

12

Published

2011

Size

998 kb

Author(s)

K. K. Khatua, K. C. Patra & P. Nayak

Abstract

During uniform flow in an open channel, the resistance is dependent on a number of flow and geometrical parameters. The usual practice in one dimensional flow analysis is to select an appropriate value of roughness coefficient for evaluating the carrying capacity of natural channel. This value of roughness is taken as uniform for the entire surface and for all depths of flow. However, it is observed that the resistance coefficients for meandering channels are found to vary with flow depths, aspect ratio, slope and sinuosity and are all linked to the stage-discharge relationships. Although much research has been done on Manning’s n for straight channels, a last word has not been spoken on the roughness values for meandering channels. An investigation concerning the variation of roughness coefficients for meandering channels with slope, sinuosity and geometry are presented. The loss of energy in terms of Darcy–Weisbach coefficient f is evaluated. A simple equation for roughness coefficient based on dimensional analysis is modeled and tested with the recent experimental data. The method gives discharge results that are quite comparable to that of the observed values as well as with other published data. Keywords: aspect ratio, bed slope, boundary shear, Darcy–Weisbach coefficient, dimensional analysis, meandering channel, flow resistance, Sinuosity (Sr), stagedischarge relationship. 1 Introduction The energy loss in a meandering channel is influenced by the channel and flow parameters and is assumed to be lumped into a single value that is manifested in the form of a single resistance coefficient. Wrong estimation of resistance coefficient can either underestimate or overestimate the discharge carrying

Keywords

spect ratio, bed slope, boundary shear, Darcy–Weisbach coefficient, dimensional analysis, meandering channel, flow resistance, Sinuosity (Sr), stagedischarge relationship