Variation of Flow Pattern with Sinuosity in Sine-Generated Meandering Streams

The effect of channel sinuosity on flow pattern in meandering streams is investigated. The centerlines of the idealized meandering streams under consideration follow sine-generated curves, and the banks are rigid; the flow is turbulent and subcritical. This study focuses on the vertically averaged flow over a flat (horizontal at any cross section) bed formed by a granular material. The “flat bed” is viewed as the initial surface of a moveable bed at the beginning of an experiment (at time $t=0$ ). A series of laboratory flow measurements involving the systematic variation of the deflection angle ${\theta }_0$ from 30 to $110°$ , is used. It is found that every different sinuosity (every different ${\theta }_0$ ) has its own convective flow pattern, i.e., its own distribution in plan of (the $L∕2$ long) convergence–divergence zones of flow. As ${\theta }_0$ increases, a gradual change in flow pattern is observed. Two expressions defining the observed ${\theta }_0$ variation of the convective flow pattern are introduced. It is shown, with the aid of the sediment transport continuity equation, that the geometry of the developed bed at the end of an experiment is strongly related to the convective behavior of the vertically averaged (initial) flow over the flat bed at $t=0$ . In particular, information on the ${\theta }_0$ variation of the convective pattern of the initial flow can be used to estimate the location of erosion–deposition zones and the location(s) of the most intense erosion–deposition corresponding to any ${\theta }_0$ .