DEVELOPMENT OF OPTIMIZATION PROCEDURE IN COMPUTATIONAL HYDRODYNAMICS

本研究的目的是将计算流体力学和非线性规划的科学方法应用于船型设计问题。在1994 ~ 1995年的研究期间，在船舶阻力和流动的CFD预报、粘性流中逆问题的新公式、最优化问题在船型改进中的应用以及船模验证试验等方面取得了进展。对单位变形灵敏度系数的计算公式进行了改进，并实现了B样条函数的体型表达式。这些改进被用于优化问题中，以最小化二维物体粘性阻力。数学公式试图将二维方法扩展到三维问题。为了验证计算网格和计算结果的有效性，还开发了三维计算机图形工具。1994年财政年度致力于改进二维基本问题和三维高级问题的研究。在计算问题中，确定船体船体上的压力分布和/或尾流区的速度分布的反问题，以获得适当的船体形状。计算结果表明，该方法可推广到三维实船问题。第二个尝试是将B样条函数应用于船体的表示，并采用线性波阻计算方法，将优化方法应用于实际船型的波阻最小化问题。本文的计算结果得到了船模试验的验证，并成功地开发了多种图形模块，用于显示船体外形和计算网格，验证计算结果。这些模块也可用于其他船舶船体构型问题。

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.