Abstract
Spatially growing disturbances of the velocity and the water depth in a mixing shear layer of open channel flows are investigated by means of the plane-2D shallow water equations. The inviscid instability analysis of the basic equations with respect to the space is firstly made for the tanh-type velocity profile in order to derive the spatial amplification rate and the phase velocity of disturbances. Then the plane-2D open channel flows with slender rectangular dead zone are simulated numerically under the hydraulic conditions of experiments. In regard to the characteristics of spatial growing disturbances, it will be shown that the amplification rate, the primary frequency and the phase velocity evaluated by the calculated results are in good agreement with the instability analysis and the laboratory tests.
