Study on Optimum Body Shape of Minimum Drag in 2-Dimensional Oseen Flow.

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The present study deals with an inverse problem for obtaining body profiles with minimum viscous drag. In the preceeding first year, the authors applied an inverse procedure for drag minimization developed by the co-investigator, Prof. Bessho, to two-dimensional Oseen flow, and obtained symmetric optimum profiles about the origin. This second year, the method has veen extended to fore-aft asymmetric profiles with minimum drag under several restriction conditions. Numerical results and discussions on the optimum profiles are made.The procedure to find optimum profiles is an iterative method. The flow quantities for a given profile are firstly determined by integral equations using Oseen's kernel functions, and are numerically solved by a panel method. Then the optimum deformation is determined so that the drag is minimized, in which the governing equation is also expressed by a set of integral equations and the solution is obtained in the same way as the former step. Then the body profiles is deformed to obtain a new profile. This procedure is iterated until a convergence is reached.The optimum profiles thus obtaind are entirely coincide with those in the first year. For the case of center of profile and length prescribed, a new optimum profile of fore-aft asymmetric shape is obtained.