Abstract: The study on bend flow is important for the development of rivers, sediment protection and river evolution. If the numerical simulation can be effectively used to reveal the law of flow and scouring and silting on bed surface, it will save a lot of manpower, money and time. In this study, two kinds of curves slow-round-slow bend and symmetric convex curves, which can be introduced to decrease the impact force of the current and to prevent scouring along the river bed, dike and feet of the dike. Through the numerical analysis, some results can be concluded the ultra-high and horizontal surface slope of the slow-round-slow bend and symmetric convex curves are significantly reduced compared with the round bend; In addition to the corner imports, on cave bank, the bottom velocity of slow-round-slow bend and symmetric convex curves is less than that of the round bend, convex bank of imports and cornering near top cross-section, the flow velocity near bottom of these two bends is significantly smaller than that of the round one; The deep groove of these two inserted with graded curves is obviously shallower than that of the round bend from the figure of vertical and horizontal erosion and deposition on the bed surface.

Key words: channel bend, transition curve, circulation, deformation of erosion and deposition, three-dimensional numerical simulation