Turbulence in radial flow between parallel disks at medium and low Reynolds numbers

Abstract

The radial flow of air between two closely spaced parallel disks is studied experimentally and the behaviour of the flow, especially the turbulence decay mechanism, is examined. At high Reynolds numbers the flow resembles fully developed turbulent two-dimensional channel flow. A quasi-laminar boundary layer is found to gradually replace the viscous sublayer as the Reynolds number decreases. At low Reynolds numbers, the turbulence decays and the flow gradually approaches a laminar-type profile. The decay process is shown to be very slow and indications of a weak turbulence-generating mechanism is observed even at very low Reynolds numbers. Relaminarization, rather than being an abrupt change in the state of the flow, is an eventual outcome of the turbulence decay process.