Lamb's Slip Hypothesis — Revisited for Torsional and Cone-plate Flow

Abstract

In this paper Lamb's original idea that “slipping is resisted by a tangential force”, i.e., a proportionality between slip velocity uS and wall shear stress τ is scrutinized for torsional and cone-plate flow, respectively. While the concept itself does indeed allow far more general dependencies than uS ∝ r (which characterizes the angular slip velocity concept) it seems that neither concept can account with reality. Experimentally, the onset of slip for these flows seems to go hand in hand with the onset of instability, at least with the loss of axial symmetry.