This paper describes the conditions for initiation and maintenance of secondary currents in open channel flows. By analyzing the Reynolds equation in the wall-normal and wall-tangent directions, this study reveals that, like other types of vortices, the secondary currents are originated in the near-boundary region, and the magnitude (or strength) of secondary flow is proportional to the lateral...

A theoretical analysis is presented of viscous incompressible laminar flow in a pipe which rotates around an axis held at small angle with respect to its symmetry-axis. Analogous to the results of Barua and Benton [1, 2], solutions in closed-form are given for circulatory flows in the crosssectional plane of the pipe due to Coriolis forces in combination with Hagen-Poiseuille flow through the p...

A bi–Hamiltonian formulation for stationary flows of the KdV hierarchy is derived in an extended phase space. A map between stationary flows and restricted flows is constructed: in a case it connects an integrable Hénon–Heiles system and the Garnier system. Moreover a new integrability scheme for Hamiltonian systems is proposed, holding in the standard phase space. Date: Dipartimento di Scienze...

A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored. Recent new work by the author and colleagues of both the stead...

Let P be the set of C1 partially hyperbolic volume-preserving flows with one dimensional central direction endowed with the C1flow topology. We prove that any X ∈ P can be approximated by an ergodic C2 volume-preserving flow. As a consequence ergodicity is dense in P. MSC 2000: primary 37D30, 37D25; secondary 37A99. keywords: Dominated splitting; Partial hyperbolicity; Volume-preserving flows; ...

We introduce a way of characterizing the linking of one-dimensional minimal sets in threedimensional flows and carry out the characterization for some minimal sets within flows modelled by templates, with an emphasis on the linking of Denjoy continua. We also show that any aperiodic minimal subshift of minimal block growth has a suspension which is homeomorphic to a Denjoy continuum.  2003 Els...

Alternating laminar and turbulent helical bands appearing in shear flows between counterrotating cylinders are accurately computed and the near-wall instability phenomena responsible for their generation identified. The computations show that this intermittent regime can only exist within large domains and that its spiral coherence is not dictated by endwall boundary conditions. A supercritical...