title: Bilateral shear layer between two parallel Couette flows.
abstract: We consider an unusual shear layer occuring between two parallel Couette flows. Contrary to the classical free shear layer, the width of the shear zone does not vary in the streamwise direction but rather exhibits a lateral variation. Based on some simplifying assumptions, an analytic solution is derived for this shear layer. These assumptions are justified by a comparison with numerical solutions of the full Navier-Stokes equations, which accord with the analytical solution to better than 1% in the entire domain. An explicit formula is found for the width of the shear zone as a function of the wall-normal coordinate. This width is independent of the wall velocities in the laminar regime. Preliminary results for a cocurrent laminar-turbulent shear layer in the same geometry are also presented. Shear-layer instabilities are then developed and result in an unsteady mixing zone at the interface between the two cocurrent streams.
authors.affiliation: Fluids Engineering Division, Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491 Trondheim, Norway.
authors.forename: Vagesh D
authors.initials: VD
authors.lastname: Narasimhamurthy
authors.forename: Simen Å
authors.initials: SÅ
authors.lastname: Ellingsen
authors.forename: Helge I
authors.initials: HI
authors.lastname: Andersson