A New Systematic Series of Foil Sections with Parallel Sides
Journal article, 2020

Parallel-sided foil sections are used for centerboards and rudders in sailing dinghy classes and also for struts placed in a fluid flow. The objective of this work is to create a systematic series of parallel-sided sections to be used under different conditions, with an emphasis on the sailing dinghies 470, 420 and Optimist. The loss, and surprisingly the gain, in performance relative to 4-digit NACA sections are also investigated. A 2D Reynolds-averaged Navier–Stokes solver is used with the k-! SST turbulence model and the gamma transition criterion. A verification study is carried out based on four grids of systematically varied density, and results compared with experimental data on a NACA 64-006 section. The parallel-sided sections are modeled with rational Bézier curves whose geometrical parameters permit to link the shape of the profile to physical variables, which are systematically varied. Three Reynolds numbers and two angles of attack are investigated. Systematic plots show the influence of the trailing edge angle and nose radius for the different section families, and the optimum combination is presented in a table. Physical explanations of the trends, and of the exceptions, are given in the paper, using flow visualizations as well as pressure and friction plots.

low Reynolds number





gamma transition criterion

systematic investigation


Bézier curves


Antonio Saporito

University of Palermo

Adam Persson

Chalmers, Mechanics and Maritime Sciences, Marine Technology

SSPA Sweden AB

Lars Larsson

Chalmers, Mechanics and Maritime Sciences, Marine Technology

Antonio Mancuso

University of Palermo

Journal of Marine Science and Engineering

2077-1312 (ISSN)

Vol. 8 9 677

Subject Categories

Mechanical Engineering

Fluid Mechanics and Acoustics

Driving Forces

Sustainable development

Areas of Advance


Health Engineering


C3SE (Chalmers Centre for Computational Science and Engineering)



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