Momentum Dispersion in Free Surface Flows through Rectangular Open-Channels with Rough Beds

摘要

In the present work, in a first step, the effects of secondary motions on the transverse distribution of the depth average velocity in free surface flows above non uniform bottom roughness is illustrated by simulations based on an anisotropic algebraic Reynolds stress model (3D). These 3D-simulations were applied to determine the wall friction and the dispersion terms present in the depth average momentum equation. In a second step, closure assumptions of these terms were tested to define a 2D-Saint Venant model which is solved to calculate the transverse profile of the depth averaged velocity. This process could allow analyze of scale change problems.