ABSTRACT
A summary of new knowledge relating to the structure of boundary layer turbulence is given. Particular emphasis is placed on recent research by the author and other investigators which has made use of elaborate flow visualisation and conditional sampling techniques in quantitative analysis. This work has confirmed the presence of coherent eddy patterns embedded in the flow, which appear to take the general form of combinations of contorted single or amalgamated groupings of vortex loop type structures. These play a crucial role in the processes of turbulence generation and the transport of momentum and contaminants such as bed sediment. The primary influence on the mechanics of the progressive modes of sediment transport, is illustrated by reference to specific research studies carried out by the author concerned with the initial instability, bed load transport and suspended load transport of fine bed sand. Links between these investigations and the transport of sediment by superimposed waves and currents are also briefly discussed.
