What methods are used for open channel velocity profiling?
A particle of water near the conduit wall will not move as fast as a particle toward the center. To understand this, take the molecules of moving liquids as an example. The first layer of molecules stick to the wall of the conduit. The next layer will move by sliding across the first layer. This happens throughout the flow with each successive layer moving at a faster velocity. The change in velocity is greater near the conduit wall than it is toward the center. If velocity measurements of each layer could be taken, a velocity profile would be produced. Velocity decreases near the surface. Because most flows fit this profile, this is called the typical profile. There are, however, situations which will cause other profile shapes and it is usually more difficult to calculate flow with these shapes. To calculate flow, an average or mean of all the varying velocities must be determined. Because it is not practical to measure the velocity of each layer of molecules, methods have been devel
