Sensitivity Analysis of an Airfoil Simulation Using Automatic Differentiation.
Derivatives are not only useful in sensitivity analysis but play a vital role in various areas of computational science including parameter optimization of computer models. Among the various methods for obtaining derivatives, automatic differentiation (AD) combines freedom from approximation errors, high performance, and the ability to handle arbitrarily complex codes arising from large-scale scientific investigations. In this note, we show how AD technology can aid in the sensitivity analysis of a computer model of an aircraft. To this end, the software tool ADIFOR, implementing the AD technology for functions written in Fortran 77, was applied to a large-scale computational fluid dynamics solver, TFS, developed at Aerodynamisches Institut, Aachen University of Technology. This solver comprises approximately 24,000 lines of Fortran 77 and is able to resolve steady and unsteady laminar and turbulent flows in two and three dimensions.