Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 07, 2019 - November 08, 2019
The effect of regularly arrayed cubes on turbulent flow is investigated using large-eddy simulation. The cubes arranged in a square array are used for an urban canopy to simplify the turbulent phenomenon. In street side, the streamwise flow speed gradually decreases, but becomes constant after the fifth row. In canyon side, a circulating vortex is generated by separation flow from the cubes, and an outflow from the canyon side to the street side is observed near the ground surface. In the turbulent flow after the second row, not only the separation from the cubes but also flow crossing between cubes with a low frequency is generated due to the effect of square arrangement of cubes. The peak frequency of power spectra of the spanwise velocity fluctuations between cubes sifts toward the lower frequency as the fetch increase, and becomes constant after fifth row. This is the same behavior as the decrease in the streamwise velocity at the street side. Turbulent flows linked with street side and canyon side are generated because the peak frequency of the spectra of the streamwise velocity fluctuation at the street side coincides with that at the canyon side at each row. This turbulent flows eventually rise above the cubes.
