Energy and Momentum Coefficients in Straight Symmetric Compound-Channel Flows

Generally, the natural rivers or sometimes the artificial channels are composed of a deep main channel with one or two shallow flood plains. The flow situation must be a 3D condition, while on purpose of hydraulic management, it is necessary treated as 1D to calculate the corresponding hydraulic characteristics. And the energy and momentum coefficients to correct the effect of non-uniformity of velocity distribution are needed to adopt. In this paper, the straight symmetric compound-channel flow is researched beginning with dimensional analysis to find the variables affecting these two coefficients. The main factors, such as the reciprocal of Reynold’s number and cross-section shape including water depth and main channel width, influencing the phenomena of the two coefficients in main channel, flood plain and total section are analysed and discussed.