Non-equilibrium Characteristics Of Bar Geometory On Bed With Non-uniform Sediment

摘要

Alternate bars on beds with non-uniform sediments are difficult to reach an equilibrium state under some hydraulic conditions. It seems likely that sediment sorting is responsible for the instability of alternate bar bed geometry, because sediment sorting affects local sediment discharge resulting in difference bed geometry. In the present study, the mechanism of the spatiotemporal change of geometric and migration characteristics of alternate bars formed on beds with non-uniform sediment is discussed in terms of numerical analysis and linear bed instability analysis. The results support the notion that alternate bars fail to reach an equilibrium state because of coexist of the same-scaled complex migration velocities.