Large-scale and very-large-scale motions in turbulent pipe flow

Abstract

In the outer region of fully developed turbulent pipe flow very large-scale motions reach wavelengths more than 8, as the combination of all smaller motions, including the large-scale motions and the main turbulent motions. The main turbulent motions, defined as the motions small enough to be in a statistical equilibrium (and hence smaller than the large-scale motions) contribute relatively little to the Reynolds shear stress, but they constitute over half of the net Reynolds shear force.