Numerical Analysis of Granular Jet Impact


We investigate impact processes of granular jets on a fixed wall, in both two (2D) and three dimensions (3D) numerically, by using Discrete Element Method, to study the fluid state after the impacts. We found the following properties of the impact processes of granular jets. (i) In 3D, the equation of states and the shear viscosity are consistent with the kinetic theory, while the shear stress is much smaller than normal stresses, thanks to the small strain rate [1, 2]. (ii) In 2D, because grains are well packed, the asymptotic divergence of the pressure or the shear viscosity similar to the jamming transition, appears [3]. (iii) In 2D, for bidispersed systems, the effective friction constant defined as the ratio between shear stress and normal stress, monotonically increases from near zero, as the increment of the strain rate. On the other hand, the friction constant has two metastable branches for mono-disperse system because of the coexistence of a crystallized state and a liquid state [3]. (iv) Both in 2D and 3D, there exist large normal stress differences, which cannot be observed in the perfect fluid.

[1] T. G. Sano and H. Hayakawa, Phys. Rev. E 86, 041308 (2012).
[2] T. G. Sano and H. Hayakawa, Powders & Grains 2013, in press (arXiv:1211.3533).
[3] T. G. Sano and H. Hayakawa, arXiv: 1302.6734.

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