A Godunov method for localization in elastoplastic granular flow

Numerical investigation of efficiency of UNO- and TVD-modifications of the Godunov method of the second order accuracy for computation of linear waves in an elastic body in comparison with the classical Godunov method is carried out. To this end, one-dimensional cylindrical Riemann problems are considered. It is shown that the both modifications are considerably more accurate in describing radially converging as well as diverging longitudinal and shear waves and contact discontinuities both in one- and two-dimensional problem statements. At that the UNO-modification is more preferable than the TVD-modification because exact implementation of the TVD property in the TVD-modification is reached at the expense of “cutting” solution extrema.

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Dilute-to-dense flow transition and flow-rate behavior of lateral bifurcated granular flow

Powder Technology ◽

10.1016/j.powtec.2021.01.060 ◽

2021 ◽

Vol 383 ◽

pp. 536-541

Author(s):

Xiaoyan Zhou ◽

Shikun Liu ◽

Zihan Zhao ◽

Xin Li ◽

Changhao Li ◽

...

Keyword(s):

Flow Rate ◽

Granular Flow ◽

Flow Transition ◽

Dense Flow ◽

Rate Behavior

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Stress level effect on mobility of dry granular flows of angular rock fragments

Landslides ◽

10.1007/s10346-021-01687-5 ◽

2021 ◽

Author(s):

B. Cagnoli

Keyword(s):

Stress Level ◽

Granular Flow ◽

High Stress ◽

Granular Flows ◽

Flow Dynamics ◽

Small Scale ◽

Flow Volume ◽

Rock Fragments ◽

Rock Avalanches ◽

Flow Mobility

AbstractGranular flows of angular rock fragments such as rock avalanches and dense pyroclastic flows are simulated numerically by means of the discrete element method. Since large-scale flows generate stresses that are larger than those generated by small-scale flows, the purpose of these simulations is to understand the effect that the stress level has on flow mobility. The results show that granular flows that slide en mass have a flow mobility that is not influenced by the stress level. On the contrary, the stress level governs flow mobility when granular flow dynamics is affected by clast agitation and collisions. This second case occurs on a relatively rougher subsurface where an increase of the stress level causes an increase of flow mobility. The results show also that as the stress level increases, the effect that an increase of flow volume has on flow mobility switches sign from causing a decrease of mobility at low stress level to causing an increase of mobility at high stress level. This latter volume effect corresponds to the famous Heim’s mobility increase with the increase of the volume of large rock avalanches detected so far only in the field and for this reason considered inexplicable without resorting to extraordinary mechanisms. Granular flow dynamics is described in terms of dimensionless scaling parameters in three different granular flow regimes. This paper illustrates for each regime the functional relationship of flow mobility with stress level, flow volume, grain size, channel width, and basal friction.

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