roughness Reynolds number

The friction factor for the turbulent flow in pipes is the binary nonlinear function of Reynolds number and relative roughness. Calculating friction factor by implicit Colebrook equation have to use iterative algorithm, which is discommodious.

管内湍动流体摩擦因数是雷诺数和相对粗糙度的二元非线性函数，由Colebrook隐式方程计算摩擦因数要用迭代的方法求解，很不方便。

The relationships for hydro-dynamic parameters ( Reynolds number, Froude number, resistance coefficient and flow velocity) of overland flow as a function of bed roughness, flow discharge and slope gradient were simulated by means of indoor fixed-bed resistance experiments.

在室内试验的基础上，采用定床阻力试验研究了坡面流水力学参数（雷诺数、佛汝德数、阻力系数和流速）随床面糙率、流量和坡度的变化规律。

Reynolds Number and Froude number of overland flow tend to diminish, water flow velocity tends to diminish, and resistance coefficient tends to increases as bed surface roughness increases in the condition of same slope gradient and flow discharge.

在坡度和流量相同情况下，随着坡面粗糙度增加，坡面流雷诺数和佛汝德数均呈减小趋势；

The resistance of surface flow has a reverse relation with Reynolds number. With the same Reynolds number, the resistance coefficient of surface flow is greater than that of laminar flow in open channel and increases with increased bed roughness.

坡面水流阻力与雷诺数的呈反比关系，相同雷诺数条件下，阻力系数比明渠层流阻力系数要大，且随床面粗糙度的增加而增大。