Author(s): Daiuske Kobayashi; Tatsuhiko Uchida

Linked Author(s): Daisuke Kobayashi, Tatsuhiko Uchida

Keywords: Undular jump; Submerged jet; Channel meander; Secondary flow; Negative step

Abstract: The flow structure in the downstream bend of a negative step was studied through experiments and threedimensional (3-D) numerical calculations, and the different risk of riverbank erosion due to various types of hydraulic jumps was discussed. Comparison with the experimental results for straight and meandering channels showed that the 3-D simulation using the standard k- model reproduced well the longitudinal distribution of water depth in the downstream bend of the negative step. The results of the cross-sectional velocity distribution in the meandering channel showed that the velocity distribution at the bend was different between the submerged jet and wave jump and that the secondary flow of the wave jump was stronger than that of the submerged jet. This is because the vertical gradient of the streamwise velocity distribution is larger and that of the centrifugal force difference is also larger compared to the case without the negative step. Therefore, when the wave jump occurs at the bend downstream of the negative step, a strong secondary flow is generated, which may increase the risk of riverbank erosion along the outer banks.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0301-cd

Year: 2023