Energy Expenditure in Curved Open Channels

Abstract

This paper describes linear partitioning of energy expenditure in curved open channels. An analytical method which predicts energy losses due to longitudinal resistance and transverse circulation is presented; predicted results are compared with measurements. The transverse energy loss is evaluated using the velocity field of transverse circulation which is implicitly dependent on the internal turbulent shear and boundary roughness; thus, direct evaluations of the shear and boundary losses are avoided. Transverse circulation is often referred to as secondary circulation as its velocity component is generally substantially lower than the longitudinal or primary velocity. Such is not the case for the energy expenditure. The loss due to transverse circulation may be of the same order of magnitude as the longitudinal loss at a higher depth to radius ratio or lower channel roughness, or both.