The thickness of the viscous sublayer in a turbulent boundary layer

A model of flow in turbulent boundary layers which postulates that the wall region consists of two zones with different types of flow, separated by an irregularly shaped boundary, is analyzed. The change of the instantaneous position of this boundary with time is assumed to be due to alternation of these two flows. In the zone directly adjoining the wall the flow of quasilaminar, and the thickness of this zone is defined by the local critical Reynolds number. The thickness of the viscous sublayer in the turbulent boundary layer defines to the mean position of the interface between the two zones. The suggested flow model explains the experimentally observed peak of velocity fluctuations in the vicinity of the boundary of the viscous sublayer, and also certain features in the behavior of statistical flow properties.