CRPC-TR94404

Title:    APPLICATIONS OF AUTOMATIC DIFFERENTIATION IN CFD

Authors:  Alan Carle, Lawrence L. Green, Christian H. Bischof
	  and Perry A. Newman

Date:     April 1994


Of the authors listed above, please indicate which are:

  Minority authors:

  Female authors:    

  Student authors:   


Keywords (list up to 8):

  Automatic Differentiation, Computational Fluid Dynamics, ADIFOR

Abstract:

  Automated multidisciplinary design of aircraft requires the
  optimization of complex performance objectives with respect to a
  number of design parameters and constraints. The effect of these
  independent design variables on the system performance criteria can be
  quantified in terms of sensitivity derivatives for the individual
  discipline simulation codes. Typical advanced CFD codes do not provide
  such derivatives as part of a flow solution. These derivatives are
  expensive to obtain by divided differences from perturbed solutions,
  and may be unreliable, particularly for noisy functions. In this
  paper, automatic differentiation has been investigated as a means of
  extending iterative CFD codes with sensitivity derivatives. In
  particular, the ADIFOR automatic differentiator has been applied to
  the 3-D, thin-layer Navier-Stokes, multigrid flow solver called TLNS3D
  coupled with the WTCO wing grid generator. Results of a sequence of
  efforts in which TLNS3D has been successfully augmented to compute a
  variety of sensitivities are presented. It is shown that sensitivity
  derivatives can be obtained accurately and efficiently using ADIFOR,
  although significant advances are necessary for the efficiency of
  ADIFOR-generated derivative code to become truly competitive with
  hand-differentiated code.

Publication History:

  Submitted to: 

  Published in:  To be published in the Proceedings of the 25th
		 AIAA Fluid Dynamics Conference, Colorado Springs,
		 June 1994