Accession Number : ADA323731

Title :   Aerodynamic Design Optimization on Unstructured Grids with a Continuous Adjoint Formulation.

Descriptive Note : Contract rept.,

Corporate Author : INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA

Personal Author(s) : Anderson, W. K. ; Venkatakrishnan, V.

PDF Url : ADA323731

Report Date : JAN 1997

Pagination or Media Count : 47

Abstract : A continuous adjoint approach for obtaining sensitivity derivatives on unstructured grids is developed and analyzed. The derivation of the costate equations is presented, and a second-order accurate discretization method is described. The relationship between the continuous formulation and a discrete formulation is explored for inviscid, as well as for viscous flow. Several limitations in a strict adherence to the continuous approach are uncovered, and an approach that circumvents these difficulties is presented. The issue of grid sensitivities, which do not arise naturally in the continuous formulation, is investigated and is observed to be of importance when dealing with geometric singularities. A method is described for modifying inviscid and viscous meshes during the design cycle to accommodate changes in the surface shape. The accuracy of the sensitivity derivatives is established by comparing with finite-difference gradients and several design examples are presented.

Descriptors :   *EULER EQUATIONS, *NAVIER STOKES EQUATIONS, *INVISCID FLOW, *VISCOUS FLOW, ALGORITHMS, OPTIMIZATION, COMPUTER AIDED DESIGN, GRIDS, ACCURACY, FINITE DIFFERENCE THEORY, COMPRESSIBLE FLOW, FLOW FIELDS, EQUATIONS, PRESSURE DISTRIBUTION, AERODYNAMICS.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE