Accession Number : ADA115151

Title :   An Optimization Technique for the Development of Two-Dimensional Steady Turbulent Boundary Layer Models.

Descriptive Note : Technical rept.,

Corporate Author : LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS

Personal Author(s) : Yuhas,L J ; Walker,J D A

PDF Url : ADA115151

Report Date : Mar 1982

Pagination or Media Count : 62

Abstract : A procedure for the development of a simple boundary layer turbulence model to account for different physical effects is described; the method is applied here to produce models for both pressure gradient and mainstream turbulence effects. Asymptotic theory is used to isolate the leading terms in an expansion for the mean velocity profile for high Reynolds numbers for both the inner and outer regions of a nominally steady two-dimensional boundary layer. The velocity profile in the outer layer satisfies a partial differential equation containing a Reynolds stress term and this term is modeled by a simple eddy viscosity function which contains two parameters. The velocity profile in the inner wall layer is modeled using an analytical expression which has been previously derived by consideration of the observed characteristics of the time-dependent flow in the wall layer and which contains a single independent parameter. For a self-similar flow, the outer layer equation becomes an ordinary differential equation; this equation is solved numerically and in conjunction with the analytical inner layer profile, a composite profile spanning the entire boundary layer is defined. This composite profile contains three parameters which may be adjusted systematically to obtain a best fit to a given set of experimental data. A computer optimization code is described in which any or all of the three profile parameters may be varied.

Descriptors :   *Turbulent boundary layer, *Optimization, Reynolds number, Pressure gradients, Eddies(Fluid mechanics), Viscosity, Asymptotic series, Computer programs, Two dimensional, Physical properties, Differential equations, Mathematical models

Subject Categories : Numerical Mathematics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE