Size invariance of the granular Rayleigh-Taylor instability

Jan Ludvig Vinningland (1) , Øistein Johnsen (1) , Eirik Grude Flekkøy (2) , Renaud Toussaint (3) , Knut Jørgen Måløy (1)

1 Department of Physics [Oslo]
2 PoreLab [Oslo]
3 IPGS - Institut de physique du globe de Strasbourg

The size scaling behavior of the granular Rayleigh-Taylor instability ͓J. L. Vinningland et al., Phys. Rev. Lett. 99, 048001 ͑2007͔͒ is investigated experimentally, numerically, and theoretically. An upper layer of grains displaces a lower gap of air by organizing into dense fingers of falling grains separated by rising bubbles of air. The dependence of these structures on the system and grain sizes is investigated. A spatial measurement of the finger structures is obtained by the Fourier power spectrum of the wave number k. As the size of the grains increases the wave number decreases accordingly which leaves the dimensionless product of wave number and grain diameter, dk, invariant. A theoretical interpretation of the invariance, based on the scaling properties of the model equations, suggests a gradual breakdown of the invariance for grains smaller than ϳ70 m or greater than ϳ570 m in diameter.

Domaines: Matière Condensée [cond-mat]; Mécanique [physics]

Jan Ludvig Vinningland, Øistein Johnsen, Eirik Grude Flekkøy, Renaud Toussaint, Knut Jørgen Måløy. Size invariance of the granular Rayleigh-Taylor instability. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2010, 81 (4), ⟨10.1103/PhysRevE.81.041308⟩. ⟨hal-02377790⟩