Local scour around circular cylinder with riblet under clear water scour condition

Asai et al. have proposed a cylinder with multi riblets in order to improve the lack of a cylinder with single riblet proposed by Saito et al. Asai et al. investigated the characteristics of the local scour with them under the hydraulic condition fixed to one type. In this paper, the dependences of the local scour with a cylinder having multi riblets on the experimental parameters which are the Froude number, cylinder types, a width of a riblet, water depth are discussed. The experimental parameters are varied systematically, and the clear water scour experiments are conducted. The characteristics of the local scour are influenced strongly by the Froude number Fr. When Fr=0.3, the reduction effect of the local scour decreases as the ratio of water depth to a diameter of the cylinder H/D increases. On the other hand, the dependences on H/D are not so much large when Fr=0.4.

local scour

riblet

clear water scour

maximum scour depth