22nd IAHR-APD CONGRESS 2020 IN SAPPORO

Session3: Environmental Hydraulics

3-11

Title: A INVESTIGATION OF THE DRAG COEFFICIENT IN A OPEN CHANNEL WITH GROUP OF COLUMNS

Muneyuki Aoki, Mutsumi Sakama, Daiki Akema


The CD of the single column and group of columns has been calculated to be approximately 1.0 using uniform flow velocity. It has been pointed out that the CD of the group of columns is not constant due to the fact that the reproducibility drops when calculating the CD of the group of columns constantly and due to the irregular flow past the group of columns. Therefore, it is necessary to make clear the CD of individual columns constituting of group of columns or the entire group of columns, to reproduce the flow in the group of columns. In this study, numerical analyses and experiments were carried out to reproduce the flow in the group of columns and verify the CD. As the results, when the CD is 1.0, the experimental result could not be reproduced. Therefore, it was calculated using the CD of the entire group of columns. However, result could not reproduce experimental results. By using CD of the entire group of columns, reproduction rate improved by about 20 (%). In conclusion, since there was a place where the flow velocity remarkably decreased within the group of columns, the CD was not constant. In addition, the ultimate purpose of this study is to reproduce a flow around the group of columns exactly and to carry out the fish habitat assessment in greater detail.





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