Application of Michell’s Integral to High-Speed Round-Bilge Hull Forms

Abstract

Computational fluid dynamics (CFD) techniques are becoming increasingly popular in analyzing fluid flow problems in almost all branches of engineering, especially in resistance prediction of ships where complex fluid flow exists, although absolute accuracy is still limited. Application of CFD techniques in resistance prediction of ships is no longer new and is being enthusiastically embraced by researchers as can be seen from articles in journals and conference proceedings. Although the towing tank tests provide better absolute accuracy, modification to hull forms is limited, resulting from both practical and financial constraints. In this respect, CFD techniques and theoretical formulations have an added advantage in the sense that rapid modifications to hull forms can be carried out and results can be obtained, so that a comparative study could be made within a few hours. In this way, a naval architect is in a better position to select a hydrodynamically efficient design. Furthermore, robust and fast hydrodynamic computational methods are essential elements of advanced numerical optimization techniques. A good high-speed design should have favorable resistance qualities, so that operational capabilities are not degraded. Innumerable investigations available in the literature enumerate resistance prediction of systematic series of high-speed hull forms. In this article, the results of a comparative study on resistance of high-speed round-bilge hull forms using CFD techniques, theoretical analysis, and experimental results have been presented. The need for better hull forms and the increased interest in resistance performance call for better data and efficient algorithms to be available at the design and optimization stage to obtain the right balance between resistance and other conflicting requirements. This article provides a study of the following. The result of modeling in SHIPFLOW, which uses a combined potential-flow boundary-layer viscous-flow zonal approach. Application of a fast resistance estimation method with the wave-making resistance by Michell’s integral, the friction resistance by International Towing Tank Conference 1957. Application of Michell’s integral to determine the wave resistance of the systematic series models. Comparison between the total resistance coefficients obtained from experimental work, SHPFLOW, and the fast resistance estimation method.