The first two are indirect methods in as much as they rely on measurements of overall torque or resistance and boundary layer similarity laws to obtain DU+, whereas the velocity profile method provides a direct measurement of DU+.

• 首两个是间接的方法一样因为他们依靠的测量整体扭矩或阻力和边界层相似性法律以取得杜+而流速剖面法提供了一个直接测量杜+。