Buoyancy-driven flow through a bed of solid particles produces a new form of Rayleigh-Taylor turbulence

G. Sardina; L. Brandt; G. Boffetta; A. Mazzino

doi:10.1103/physrevlett.121.224501

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arXiv · 1902.01123

Buoyancy-driven flow through a bed of solid particles produces a new form of Rayleigh-Taylor turbulence

G. Sardina·L. Brandt·G. Boffetta·A. Mazzino

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Abstract

Rayleigh--Taylor fluid turbulence through a bed of rigid, finite-size, spheres is investigated by means of high-resolution Direct Numerical Simulations (DNS), fully coupling the fluid and the solid phase via a state-of-the art Immersed Boundary Method (IBM). The porous character of the medium reveals a totally different physics for the mixing process when compared to the well-known phenomenology of classical RT mixing. For sufficiently small porosity, the growth-rate of the mixing layer is linear in time (instead of quadratical) and the velocity fluctuations tend to saturate to a constant value (instead of linearly growing). We propose an effective continuum model to fully explain these results where porosity originated by the finite-size spheres is parameterized by a friction coefficient.

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G. Sardina, L. Brandt, G. Boffetta, A. Mazzino. 2019-02-04. Buoyancy-driven flow through a bed of solid particles produces a new form of Rayleigh-Taylor turbulence. https://doi.org/10.1103/physrevlett.121.224501

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