Published online by Cambridge University Press: 04 July 2016
The majority of current prediction procedures for turbulent flows employ models of turbulent momentum transfer which calculate an effective viscosity for μeff such that for a boundary-layer flow the shear stress, τ, is given by:
A number of recent experimental investigations (ref. 1-3 for example) have found, however, that in strongly asymmetric turbulent flows, τ is finite where the mean velocity gradient is zero—and vice versa. These phenomena, which are evidently not describable in terms of an effective viscosity hypothesis, point the need for a more complete description of turbulent motion.