直列配列された直方体ブロック周りの乱流構造

抄録

The mechanism of the low-frequency turbulent flow in an urban canopy formed by series of cuboids is investigated using large-eddy simulation. Three different types of blocks (cubic, vertical rectangle, and horizontal rectangle) was used to investigate the turbulent behavior around series of cuboids in the first, second, third, fifth, seventh and tenth rows. In the vertical rectangle with a double height, the low-frequency turbulent flow is generated at the second row, but in the horizontal rectangle with a double width it is generated at the first row. The peak frequency of the power spectra of the velocity fluctuation moves toward the low frequency as the fetch increases, and the peak frequency becomes constant beyond a certain row. The peak frequency of the energy spectra becomes larger as the block height increases, and becomes smaller as the block width increases. The peak frequency of the power spectra of the spanwise velocity fluctuation between the cuboids coincides with the peak frequency of the power spectra of the streamwise velocity fluctuation side the cuboid. It indicates that the turbulent flow side the blocks strongly affects the low-frequency turbulent flow between cuboids.