Changing and swing of the axisofflow power is normality.
该河段水流的动力轴线的变化和摆动是常态。
2
The position of power axisofflow is determined by main channel when runoff is small, while the change law conforms with the law of rectangular section when runoff is large.
当小流量时水流动力轴线的位置取决于主槽的位置，当大流量时水流动力轴线的变化规律接近矩形断面的情形。
3
Consider a ball that is spinning about an axis perpendicular to the flowof air across it (see left).