6th China-Japan-Korea Joint Symposium on Optimization of Structural and Mechanical Systems

Authors: Iku Kosaka, Takeshi Kobiki, Kazuhiro Kooriyama
Publication Date: June 22-25, 2010

A design process to improve the coefficient of drag for vehicles analyzed by computational fluid dynamics (CFD) is presented. The proposed design process involves process integration and design optimization of general-purpose optimization software, CFD software, and CAD based morphing software. Since optimizations of CFD, in general, require modification of geometry and node locations, some of the biggest challenges are parameterization and process automation of geometry changes and corresponding mesh regeneration. In addition to this, optimization results need to be incorporated into a final CAD design quickly and easily once the optimization is completed. Therefore, a CAD based morphing tool, allowing direct CAD parameter optimization, is used to re-mesh a CFD model based on the CAD parameters change. Once the process integration is completed, response values are computed at the sampling points using design of experiment (DOE). Then response surface approximation (RSA) based optimization is performed to obtain an optimal solution. Three CAD parameters, which control the front deck of a vehicle, are used as design variables and coefficient of drag (CD) value is optimized to demonstrate the design process. Statistical tools are employed to evaluate the approximation of the response, and the approximated design space of CD value with respect to design variables is visualized in 3D plots to display the design space. The proposed process can provide valuable information and insight into a design space for designers and engineers during early conceptual design stages.