The effect of spatial restriction on the inner layer structure of wall turbulence.

Abstract

Hot-film anemometer measurements were carried out in a shear flow between a flat plate and a moving plate fitted with an array of tall fences. The effect of spatial restriction by the fences on the inner layer structure of the boundary layer developed on the flat-plate side was investigated. It was revealed that the inner layer structure of the wall turbulence was maintained even when the tips of the fences were passing at a distance y+=50 from the flat plate. The flow did not become laminar-like until the tips came up to y+=2030. There results provoked the physical determined under a given mean wall shear stress and is hardly influenced by outer layer disturbances provided its own spatial extent of about 50v/u* from the wall is ensured.