船の粘性抵抗に対する形状影響について : その2-二次元物体の圧力抵抗および全抵抗

概要

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As a continuation of a study on form effects on viscous resistance of ships, this paper deals with the pressure resistance of a two dimensional streamlined body. The effects of the boundary layer on pressure distribution over the surface of the body are explained, for the region of small curvature of streamline, as the sum of the displacement and the pressure thickness effects. It is shown that, at the tail end of the body with finite angle, special consideration must be paid to the action of viscous stress. It is suggested that the pressure of actual flow at the tail end may be approximated by the pressure of ideal flow at the edge of the boundary layer and the pressure resistance coefficient based on wetted surface area can be estimated by the formula 1/4α^2(δ(L))/L, where α is the full angle of the tail end, L the length and δ (L) the boundary layer thickness at the tail. Finaly an approximate method for calculating a form factor due to pressure resistance is presented.