AVS 52nd International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeM

Invited Paper VT-WeM1
Pressure Dependence of Laminar-Turbulent Transition in Gases

Wednesday, November 2, 2005, 8:20 am, Room 201

Session: Gas Flow and Pump Technology
Presenter: L.D. Hinkle, Falmouth Public Schools
Authors: L.D. Hinkle, Falmouth Public Schools
A. Muriel, World Laboratory, CERN
S.A. Novopashin, Institute of Thermophysics, Russia
Correspondent: Click to Email
The transition between the laminar and turbulent flow regimes is traditionally addressed using the continuum formulation of the Navier-Stokes equation and dimensionless parameters such as the Reynolds number. However, a detailed understanding of the transition mechanisms has remained elusive. Theoretical approaches based on molecular and quantum mechanical models have been proposed but have yet to be thoroughly tested experimentally. In an effort to test a quantum-based model, specific apparatus and experiments have been designed to evaluate particular features of the laminar-turbulent transition. The experiments and analysis examine the transitions by producing a hysteresis plot as displayed on a flow versus differential pressure graph. This has been done for the transitions occurring in a tube with a divergent entrance. The hysteresis plots generated in these tests show several notable features and quantitative trends. The primary focus of this paper is on the observed absolute pressure dependence of the transition behavior. Whereas the continuum-based model does not predict a pressure dependence of the laminar-turbulent transition, a relatively simple quantum-based model indicates a particular pressure effect on the transition to turbulent flow.