Observations regarding Use of Advanced Cfd Analysis, Sensitivity Analysis, and Design Codes in Mdo

Observations regarding the use of advanced computational uid dynamics (CFD) analysis, sensitivity analysis (SA), and design codes in gradient-based multidisciplinary design optimization (MDO) re ect our perception of the interactions required of CFD and our experience in recent aerodynamic design optimization studies using CFD. Sample results from these latter studies are summarized for conventional optimization (analysis-SA codes) and simultaneous analysis and design optimization (design code) using both Euler and NavierStokes ow approximations. The SA codes is greater than that required for design codes. Thus, an MDO formulation that utilizes the more e cient design codes where possible is desired. However, in the aerovehicle MDO problem, the various disciplines that are involved have di erent design points in the ight envelope; therefore, CFD analysis-SA codes are required at th aerodynamic \o design" points. The suggested MDO formulation is a hybrid multilevel optimization procedure that consists of both multipoint CFD analysis-SA codes and multipoint CFD design codes that perform suboptimizations. This research was supported by the National Aeronautics and Space Administration under NASA Contract NAS1-19480 while the second author was in residence at the Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, Hampton, VA 23681-0001. The work of the second and third authors was partially supported by NASA Grant NAG-1-1265.