Scale-to-scale turbulence modification by small settling particles
نویسندگان
چکیده
Despite decades of investigations, there is still no consensus on whether inertial particles augment or dampen turbulence. Here, we perform the first experimental study in which particle concentration varied systematically across a broad range volume fractions $\varPhi _{v}$ , from nominally one-way coupled to heavily two-way regimes, keeping all other parameters constant. We utilize zero-mean flow chamber where steady, homogeneous and approximately isotropic air turbulence realized, with Taylor-microscale Reynolds number $Re_{\lambda } = 150\unicode{x2013}300$ . consider spherical solid two sizes, both much smaller than Kolmogorov length, yielding Stokes numbers $St_{\eta 0.3$ 2.6 based time scale. By adjusting turbulent intensity, settling velocity parameter kept constant for cases, $Sv_{\eta V_{t}/u_{\eta }\approx 3$ (where $V_{t}$ still-air terminal velocity, $u_{\eta }$ scale). Unlike previous studies focused massively particles, find that kinetic energy increases loading, being more doubled at _{v} =5\times 10^{-5}$ This attributed input associated gravitational settling: release their potential into fluid increase its dissipation rate, while scale inter-scale transfer not strongly changed. Two-point statistics indicate energy-containing eddies become vertically elongated presence falling latter redistribute homogeneously scales compared unladen rooted an enhanced cascade, as shown by nonlinear rate.
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ژورنال
عنوان ژورنال: Journal of Fluid Mechanics
سال: 2022
ISSN: ['0022-1120', '1469-7645']
DOI: https://doi.org/10.1017/jfm.2022.762