NUMERICAL STUDY ON EFFECT OF DIFFRENCE BETWEEN SIDE WALL AND BOTTOM WALL ROUGHNESS COEFFICIENTS ON SECONDARY FLOW IN BEND CHANNEL

Abstract

 In this study, we conducted numerical experiments to investigate the influence of the wall and bed roughness to the secondary flow in a bend part in open channel flows. The nays CUBE distributed by the iRIC project was used in this study. Firstly we conformed that the nays CUBE has good accuracy to predict the three dimensional flow by comparing with our laboratory experimental data.
 We conducted numerical experiments under the five cases. In the cases that the wall roughness is smaller than or equal to the bed roughness, the circulation near the inner bank wall became bigger as the side wall roughness increased in the entrance of the bend part. On the other hand, in the cases that the wall roughness is greater than the bed roughness, the circulations near the outer bank wall were not clear at the middle of the bend part.