Author(s): B. J. Belcher; J. F. Fox

Linked Author(s): James Fox

Keywords: No Keywords

Abstract: Turbulent bursting, large eddies, secondary currents and other coherent fluid motions are important physical processes in gravel-bed rivers. Here, experimental measurements of velocity fields in gravel-bed flow conditions in the laboratory were used to characterize temporal and spatial structure which may be attributed to these physical processes. Flow visualization using Proper Orthogonal Decomposition of Particle Image Velocimetry data was used to characterize the size, shape and spatial patterns of the turbulent structures, which were observed to be composed of vortex tubes arranged into knot patterns. Under the specific conditions of a particularly violent reconnection event and coherent macro structure formation, also termed a turbulent burst, the fluid domain may be modeled as a flux-conserving flow of prime knots formed of thin-cored flux tubes embedded on an abstract vortex surface itself having topology of a Klein manifold.

DOI:

Year: 2009