DEVELOPMENT OF OPTIMIZATION PROCEDURE IN COMPUTATIONAL HYDRODYNAMICS

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The objectives of the present research are to apply the scientific procedures of computational fluid dynamics and the nonlinear programming to the ship form design problem. During the research period of 1994 to 1995, developments have been made on CFD predictions of ship resistance and flow, a new formulation of inverse prblem in viscous flow, applications of optimization problem to the improvement of ship form, and validation experiments using ship models.In the 1993 fiscal year, improvements were made on the formulation of the sensitivity coefficients due to unit deformation of a body, and implimentation of B-spline function for the body form expression. These improvements were utilized in the optimization problem for minimizing 2-D body viscous resistance. Mathematical formulations was attempted to extend the 2-D method to 3-D problem. Developments on 3-D computer graphic tools were also attempted to examine the validity of the computational grids and the computational results.The last 1994 fiscal year has been devoted to the researches of improvement of the 2-D fundamental problem, and the 3-D advanced problems.In the computational problem, an inverse problem specifying the pressure distribution on the body hull and/or the velocity profile in the wake region for obtaining the proper body shape. The computational results have revealed that this method will safely be extented to 3-D actual ship problem. The second attempt is an application of the optimization method to the wave-resistance minimization problem for practical ship forms, by applying the B-spline function to ship hull presentation and by using linear wave resistance calculation methods. The results have been validated well by model ship experiments.Many graphic modules have successfully been developed for the presentation of the ship hull form and computational grids, and for the validation of the computational results. These modules can also be used for other ship hull configuration problems.