Minimization of Total Resistance of a Surface-Piercing Vertical Strut

Abstract

An attempt was made to obtain a surface-piercing vertical strut with minimum total resistance by means of nonlinear programming under the constraints that the beam and water plane area of the strut were kept constant. The objective function in the nonlinear programming is the sum of wave-making resistance calculated by Michell's integral and viscous resistance calculated by a higher order boundary layer theory taking the longitudinal curvature effect into consideration.In the minimization process, the strut form with minimum wave-making resistance was used as an initial form. It is a characteristic that the strut form of minimum total resistance has a fine shape near the trailing edge and the fore body has a similar shape as that of the body of minimum wave-making resistance. In the minimization process, it is shown that the viscous pressure resistance is reduced largely whereas the wave-making resistance is increased a little and frictional resistance is kept almost unchanged.