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題 名 | On the Average Settling Rate of Heavy Particles in Decaying Homogeneous Isotropic Turbulence |
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作 者 | Yang,C. Y.; Lei,U.; | 書刊名 | The Chinese Journal of Mechanics |
卷 期 | 14:3 1998.09[民87.09] |
頁 次 | 頁111-118 |
分類號 | 440.137 |
關鍵詞 | Average settling rate of particles; Decaying homogeneous isotropic turbulence; Direct numerical simulation; DNS; |
語 文 | 英文(English) |
英文摘要 | The average settling rate of spherical solid particles, <vs>, under a body force field is studied numerically in decaying homogeneous isotropic turbulent flows generated by the direct numerical simulation of the continuity and Navier-Stokes equations. The increase of the average settling rate, (△ vs), is maximized when 1 and 0.5, and is order 0.1v', which is qualitatively similar to that in stationary turbulence. Here (△ vs) = <vs> - vd, is the particle's relaxation time, is the Kolmogorov time scale, vd is the settling rate of particles in still fluid, and u' is the root mean square of the fluid velocity fluctuation. However, the magnitude of the maximum value of < △ vs> in decaying turbulence is substantially greater (about 40%) than that in the corresponding stationary turbulence due to the inertia response of particles to turbulence decay. Although < △ vs>/u' does not reach a stationary state as the flow is evolving, it is a slowly time varying function for the parameters of interest as (when < △ vs> is maximized) is in general of one order less than the time scale of turbulence decay. |
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