Determination of velocity distribution and flow resistance in vegetated channel flows

Although flow resistance is one of the oldest problems in fluid mechanics, it is still far from being fully understood and resolved. One of the examples is the determination of velocity profiles and friction factor of vegetated channel flows. The effects of instream vegetation on velocity and flow resistance remain almost unpredictable although their significance for channel flows is widely recognized by hydraulic and ecological engineers. In this paper, we redefine the hydraulic radius and roughness height, and the flow resistance is broadly divided into the skin friction and the form drag, which are proportional to the contact area and wake volume, respectively. The estimation of skin friction and form drag is obtained theoretically, and the momentum equation is solved to obtain, based on it, the velocity distribution is obtained. The measured velocity and friction factor have been used to verify these equations