砂漣に関する実験的研究(2) ―砂漣の形成に及ぼす側壁の彰響―

Abstract

Authors manufactured an equipment measuring water level and bed elevation using ultra-sonicdevice, and are conducting a series of experimental studies for the characteristics of sand waves.Sand waves on movable bed have usually three dimensional characteristics and it is consideredthat the side wall gives a large influence on their forms. In this paper, authors studiedexperimentally the side wall effects on the characteristics of sand waves. Two types areconsidered as the side wall effects, namely shear defect and the secondary current due to theside wall.For the defect of the shear stress, it could be assumed to distribute logarithmically across thechannel bottom from the mearsuement of the velocity distribution, but the effect of the non-uniformity of the shear stress distribution on sand waves was not so much.On the other hand, the secondary currents give a large influence on the deformation of sandwaves and the occurrence of the meandering flow. Authors gave some qualitative considerationabout these secondary currents.