Rectangular Lateral Weirs in Circular Open Channels

Abstract

A theoretical expression for the outflow through a rectangular lateral weir located in a circular open channel is derived using the results of an existing theory of lateral efflux through a two-dimensional conduit outlet. The development of the present model is similar to a procedure that earlier yielded the theoretical expression for the outflow through a rectangular lateral weir located in a rectangular open channel, on the basis of the free streamline theory. In the present case, the theoretical weir discharge coefficient is expressed as a function of parameters relating the geometry of the rectangular lateral weir and the circular open channel and a velocity parameter, which is a function of the dimensionless flow depth, the dimensionless weir sill height, and the Froude number of the approach flow. Experimental results are presented to verify the proposed model.