橋脚前面の渦の機構に関する実験的研究

Abstract

The horse shoe vortex arising just upstream of the bridge pier plays an important role in localscour. In order to make clear the structure of the vortex, it is important to estimate each termof the basic equation of motion and to make clear what kind of non-dinsensional value is effectivefor the vortex motion. On the result of the investigation of these matter, the dimension of thevortex and the position of the axis of the vortex are made clear by dimensional analysis of experimen-tal data. That is, it is shown that these values are expressed by function of the radius of the pier, water depth and shear velocity.On the basis of the result, it is also shown that the vertical expansion of the region of the vortexcan be analysed by use of the shear velocity as a parameter.