Accession Number : ADA290114

Title :   Numerical Investigation of Surface Curvature Effects in Compressible Turbulent Flows.

Descriptive Note : Final rept. 1 Dec 91-30 Nov 93,

Corporate Author : MCDONNELL DOUGLAS AEROSPACE ST LOUIS MO

Personal Author(s) : Kral, Linda D. ; Donovan, John F.

PDF Url : ADA290114

Report Date : 02 DEC 1994

Pagination or Media Count : 37

Abstract : The objective of this work has been to develop a direct numerical simulation capability for compressible, non-canonical wall-bounded flows which is directly applicable to actual flight vehicles. Data from the simulations is used to educe information about the organized motion. In the flow and bow they are affected by the extra strain rates due to concave wall curvature. A second-order finite volume approach and both fourth-order and sixth-order compact differences are available for the spatial derivatives. The algorithm allows for generalized coordinates so that simulations about complex geometries can be performed. Extensive testing was done for two subgrid-scale models, the compressible Smagoriusky and structure function models, for a supersonic boundary layer. As the subgrid-scale viscosity also behaves as an artificial viscosity for central differencing codes, the study reinforced the need for high-order dissipation models in the simulation code. Validation of the numerical method was performed for flow over a concave surface for subsonic flow in which streamwise vortices develop in the boundary-layer due to the Gortler instability. The geometry and flow conditions closely approximated the incompressible experiments of Swearingen and Blackwelder. The simulations captured the essential features of the experiments in which counter-rotating vortices developed near the wall. As these streamwise vortices develop, the laminar boundary layer on the concave wall rapidly becomes three-dimensional. Higher-momentum fluid is pulled towards the wall from the outer flow as vortices grow downstream. The low-speed fluid lying between the vortices induces low-momentum fluid away from the wall, leading to inflectional streamwise velocity profiles, in good agreement with the experiments. (AN)

Descriptors :   *TURBULENT FLOW, *COMPRESSIBLE FLOW, MATHEMATICAL MODELS, ALGORITHMS, COMPUTERIZED SIMULATION, DISSIPATION, EDDIES(FLUID MECHANICS), VORTICES, COMPUTATIONAL FLUID DYNAMICS, STRAIN RATE, FINITE DIFFERENCE THEORY, HYDRODYNAMIC CODES, SUBSONIC FLOW, NUMERICAL METHODS AND PROCEDURES, SUPERSONIC FLOW, BOUNDARY LAYER TRANSITION, VISCOSITY, REYNOLDS NUMBER, GAS SURFACE INTERACTIONS, INCOMPRESSIBILITY, DOWNSTREAM FLOW, THREE DIMENSIONAL FLOW, LAMINAR BOUNDARY LAYER, CONCAVE BODIES.

Subject Categories : Fluid Mechanics
      Aerodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE