CFD Based Optimal Design Method for Energy Saving Devices by Using Overset Grid Technique and Nonlinear Optimization Theory

Abstract

The present paper describes development and demonstration of CFD-based optimal design method for Energy Saving Devices (ESD), which are installed near the stern of commercial ship. Focus here is implementation of the two state-of-the-art numerical approaches, i.e., the overset grid technique and the nonlinear programing (NP) theory. Through our investigations, combination of the two is very effective in application to optimal ESD design. For the former, a practical geometry modeling method to yield new designs is successfully demonstrated in the present study. The latter is a well-validated NP numerical scheme, i,e., Successive Quadratic Programming (SQP), coded in a form of parallel architecture based on message passing interface (MPI) protocol. Together with the asynchronous evaluator model proposed in this work, the present approach offers significant advantages over other serial mode algorithms for high computational efficiency that is an apparently demanded feature for basically very time consuming CFD-based optimization problem. In the following, an overview of the present method is given, and results are presented and discussed for the twofold aims: first, to assess accuracy of the present overset grid technique through comparison with detailed experimental data; and next, to evaluate and state the effectiveness of the present approach for ESD optimal design. Finally, future prognoses and conclusion are given.