ABSTRACT
Making use of an analysis of flow over a small-amplitude smooth, wavy wall, a bedform instability analysis is worked out. The bed grains are such that the bed behaves as an hydraulically smooth boundary. The effect of gravity is included in the instability work through the local inclination of the bed. It was found that the bed is unstable for a particular range of wavenumbers. The range of the most unstable wavenumbers gives a range of wavelengths at which one would expect a bed disturbance to grow. Agreement with available limited ripple data has been observed.
