TY - JOUR
T1 - Turbulence structure of multiscale generated turbulence by fractal grids and scalar transfer mechanism (2nd report, DNS on the influence of grid parameters on homogeneity, isotropy and intermittency)
AU - Suzuki, Hiroki
AU - Nagata, Kouji
AU - Sakai, Yasuhiko
AU - Hayase, Toshiyuki
PY - 2010/12
Y1 - 2010/12
N2 - Turbulence characteristics in the spatially developing fractal-generated turbulence are investigated by means of the direct numerical simulation (DNS). The square type fractal grids are numerically constructed using the immersed boundary method. The effects of solidity σ and thickness ratio t r, which are ones of the most important grid parameters for fractal grids, are investigated in detail. The results show that the increase of a leads to the improvement of the uniformity and isotropy of flow fields. The integral length scale in the decaying region of the fractal-generated turbulence remains monotone increase at high σ and tr, whereas it is approximately constant at low σ and tr. The derivative skewness and flatness in the streamwise direction are different from those in the transverse direction for all σ and tr investigated. These results will be useful for designing fractal grids for practical applications.
AB - Turbulence characteristics in the spatially developing fractal-generated turbulence are investigated by means of the direct numerical simulation (DNS). The square type fractal grids are numerically constructed using the immersed boundary method. The effects of solidity σ and thickness ratio t r, which are ones of the most important grid parameters for fractal grids, are investigated in detail. The results show that the increase of a leads to the improvement of the uniformity and isotropy of flow fields. The integral length scale in the decaying region of the fractal-generated turbulence remains monotone increase at high σ and tr, whereas it is approximately constant at low σ and tr. The derivative skewness and flatness in the streamwise direction are different from those in the transverse direction for all σ and tr investigated. These results will be useful for designing fractal grids for practical applications.
KW - Computational fluid dynamics
KW - Direct numerical simulation
KW - Finite difference method
KW - Fractal
KW - Grid-Generated turbulence
KW - Turbulence
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U2 - 10.1299/kikaib.76.772_2024
DO - 10.1299/kikaib.76.772_2024
M3 - Article
AN - SCOPUS:79953208037
SN - 0387-5016
VL - 76
SP - 2024
EP - 2031
JO - Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
JF - Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
IS - 772
ER -