Author(s): Sung-Uk Choi; Younghoon Joung
Linked Author(s): Sung-Uk Choi
Keywords: Direct numerical simulation; Secondary flows; Rectangular channel flows; Compound channel flows; Mean streamwise velocity; Wall shear stress
Abstract: In the present study, DNS data of rectangular and compound open-channel flows are provided to investigate the impact of secondary flows on the flow structure. In the mean velocity field from the DNS data, strong secondary flows are observed near the specific wall region, and they appear to affect significantly the distribution of the mean streamwise velocity. For both rectangular and compound open-channel flows, it is found that the mean streamwise velocity does not satisfy the log-law in the region where the strong secondary flows are generated. Also, the wall shear stress from the present DNS data and LES data in the literature shows a peak at the free surface and at the juncture of the main channel and the floodplain for the rectangular and compound open-channel flows, respectively. However, measured data in the literature do not show the same tendency, which comes from improper estimation of the shear velocity with the experimental data.