G206 不規則粗面の粗さパラメータと摩擦抵抗との関係に関する実験的研究(GS2 乱流の諸問題,一般セッション)

Abstract

Experimental investigation on the Relationship between roughness parameter of non-uniform surface roughness and flow resistance has been carried out. In this experiment, we evaluated non-uniform surface roughness of various surface by the optical method and measured friction coefficient over each surface roughness. As an evaluation of non-uniform surface roughness, we measured surface roughness profiles of each surface by a laser displacement sensor and calculated some roughness parameters such as the root mean square roughness. One important result indicates that the friction coefficient increases logarithmically with increasing root mean square roughness. Moreover, to discuss the effect of non-uniform roughness in detail, the Probability Density Function (PDF) of the roughness height were analyzed. As a result, the frictional drag over the rough surface can be mostly evaluated by the root mean square roughness when the probability density distribution of the surface roughness profile has Gaussian distribution.