UNSTEADY FLOW MODELLING OF ALLUVIAL STREAMS• WITH FLOW. CURVATURE

Abstract

The curvature in flow in the alluvial streams near curved reach changes the geometry of the stream. Due to channel curvature, centrifugal force dominates and the transverse velocity is related to the centrifugal force, rugosity coefficient and the superelevation of the transverse water surface. Transverse flow though exists in channels of both linear and non-linear alignment, as the flow enters a curved reach, transverse flow induced by the centrifugal force is very much pronounced. The transverse circulation affects the resistance pattern of the flow and the energy expenditure in it. Transverse circulation has been seen to be responsible mainly for the transverse sediment transport in a curved open channel and the resultant bed topography. Based on the above concept, an uncoupled two dimensional gradually varied flow model has been formulated based on St. Venant equations. In order to represent two dimensional aspect of the model, the compound stream model developed by Dass and the transverse circulation model of Kikkawa et al has been used as supplementary equations alongwith other terms and coefficients to represent, a natural stream.,...