FU Hui, YANG Kai-lin, WANG Tao, GUO Xin-lei (State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China)

Abstract: Logarithmic velocity distribution formula is commonly used to calculate vertical velocity, but Karman constant K, integral constant B and coefficient of wake strength Π cannot be confirmed at present. The value range of these three parameters and their effects on velocity calculation are studied in this paper. The precision, advantages and disadvantages of different calculation methods for friction velocity u * is also discussed. Through comparing 877 calculated and experimental velocity data, it is proved that when taking K as 0.395 and B as 5.419, the logarithmic velocity distribution formula without wake strength is accurate enough to satisfy the requirements of actual engineering.

Key words: logarithmic, velocity distribution, sensitivity, parameter value

Published in: Journal of Hydraulic Engineering, Vol. 44, No. 4, 2013