Accession Number : ADA133769

Title :   Experimental Studies of Unsteady Phenomena in Boundary Layers,

Descriptive Note : Annual technical rept. 1 May 82-30 Apr 83,


Personal Author(s) : Gad-el-Hak,Mohamed

PDF Url : ADA133769

Report Date : May 1983

Pagination or Media Count : 60

Abstract : The stability of decelerating boundary layer flow is investigated experimentally and numerically. Experimentally, a flat plate having a Blasius boundary layer is decelerated in an 18-m towing tank. The boundary layer becomes unstable to two-dimensional waves which break down into three-dimensional patterns, hairpin vortices, and finally turbulent bursts when the vortices lift off the wall. The unsteady boundary layer equations are solved numerically to generate instantaneous velocity profiles for a range of boundary and initial conditions. A quasi-steady approximation is invoked and the stability of local velocity profiles are determined by solving the Orr-Sommerfeld equation using Chebyshev matrix methods. Comparisons are made between the numerical predictions and the experimentally observed instabilities. (Author)

Descriptors :   *Boundary layer flow, *Unsteady flow, *Deceleration, *Boundary layer transition, Flow visualization, Equations, Problem solving, Numerical methods and procedures

Subject Categories : Numerical Mathematics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE