We compare how a homogeneous isotropic turbulent flow (micro-scale Reynolds number Reλ ≈ 435) is modulated by finite diameter spheres and finite length fibres. Both spheres and fibres produce a similar bulk effect, characterized by a reduction of the micro-scale Reynolds number to around Reλ ≈ 220. However, a spectral analysis of the flows reveals very different stories for the two particle geometries. For spheres, the flow is modulated on scales comparable with the sphere diameter. Little modulation occurs at smaller scales, and the canonical turbulent energy cascade is recovered in this region of the spectra. While for fibres, modulation occurs over a much wider range of length-scales, (including the fibre thickness) and a new turbulent kinetic energy scaling E ∼ κ-1 is found in the place of the canonical cascade.
MODULATION OF HOMOGENEOUS ISOTROPIC TURBULENCE BY DISPERSED FIBRES AND PARTICLES
Olivieri S.;
2022-01-01
Abstract
We compare how a homogeneous isotropic turbulent flow (micro-scale Reynolds number Reλ ≈ 435) is modulated by finite diameter spheres and finite length fibres. Both spheres and fibres produce a similar bulk effect, characterized by a reduction of the micro-scale Reynolds number to around Reλ ≈ 220. However, a spectral analysis of the flows reveals very different stories for the two particle geometries. For spheres, the flow is modulated on scales comparable with the sphere diameter. Little modulation occurs at smaller scales, and the canonical turbulent energy cascade is recovered in this region of the spectra. While for fibres, modulation occurs over a much wider range of length-scales, (including the fibre thickness) and a new turbulent kinetic energy scaling E ∼ κ-1 is found in the place of the canonical cascade.
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