Modelling the transitional boundary layer 13; 13;

Narasimha, R (1990) Modelling the transitional boundary layer 13; 13;. Technical Report. National Aeronautics and Space Administration, Virginia, USA.

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    Abstract

    Recent developments in the modelling of the transition zone in the boundary layer are reviewed (the zone being defined as extending from the station where intermittency begins to depart from zero to that where it is nearly unity). The value of using a new non-dimensional spot formation rate parameter, and the importance of allowing for so-called subtransitions within the transition zone, are both stressed. Models do reasonably well in constant pressure 2-dimensional flows, but in the presence of strong pressure gradients further improvements are needed. The linear combination approach works surprisingly well in most cases, but would not be so successful in situations where a purely laminar boundary layer would separate but a transitional one would not. Intermittency-weighted eddy viscosity methods do not predict peak surface parameters well without the introduction of an overshooting transition function whose connection with the spot theory of transition is obscure. Suggestions are made for further work that now appears necessary for developing improved models of the transition zone.

    Item Type: Proj.Doc/Technical Report (Technical Report)
    Uncontrolled Keywords: Transitional boundary layer;Two-dimensional;Predict peak; Interrnittency-weighted;Turbulent flow
    Subjects: ENGINEERING > Fluid Mechanics and Thermodynamics
    Division/Department: Fluid Dynamics
    Depositing User: M/S ICAST NAL
    Date Deposited: 10 Nov 2006
    Last Modified: 24 May 2010 09:51
    URI: http://nal-ir.nal.res.in/id/eprint/3076

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