Rheology Of Granular Media Research Articles

Force and flow characteristics of an intruder immersed in 3D dense granular matter

The motion of a projectile impact onto a granular target results in both the resistance force exerted on the projectile and rheology of granular media. A horizontal arrangement of cylinder quasistatically and dynamically intruding into granular media under different velocities and angles is simulated using discrete element method. Three distinguished drag force regimes are exhibited, including hydrostatic-like force independent of velocity, viscous force related to velocity, and inertial drag force proportional to the square of velocity. Meanwhile, the influence of penetration angles on drag force is examined for these three regimes, and a force model, which is related to penetration depth and angle, is proposed for quasi-static penetration. Then, flow characteristics of the granular media, such as velocity field, pressure field, packing fraction etc., are traced, and a rheology model of packing fraction and inertial number is established.

A non-invasive stochastic-optical method (SOM) for estimating the volume fraction in granular flows: application on interrogation windows with different aspect ratios

Granular flows are involved in geophysical phenomena and industrial applications. The knowledge of the volume fraction is essential for better understanding their dynamics. Indeed, this quantity is highly coupled with the rheology of granular media. Here, we investigated the performance of the stochastic-optical method (SOM), proposed by [Sarno et al. Granular Matter (2016) 18: 80]. The method works thanks to highly-controlled illumination conditions, guaranteed by a flickering-free planar lamp, and uses a high-speed digital camera. Namely, the indirect estimation of the near-wall volume fraction c3D is made possible by the estimation of a quantity, called two-dimensional volume fraction c2D, which is measurable through an opportune binarization of gray-scale images. With the purpose of assessing the performance of the SOM method on rectangular interrogation windows with different aspect ratios, we present a novel experimental campaign on dispersions of matte-white plastic beads immersed in a dense fluid, where the angle of incidence of light was 25°. Moreover, we explored various settings of the binarization algorithm, incorporated in the SOM method. The accuracy of the method is found to be reasonably high with a root-mean-square error on c3D lower than 0.03 for a wide range of settings and independently from the aspect ratio.

Closure to “Quasi-Static Rheology of Granular Media Using the Static DEM” by J. Meng, J. Huang, D. Sheng, and S. W. Sloan

Closure to “Quasi-Static Rheology of Granular Media Using the Static DEM” by J. Meng, J. Huang, D. Sheng, and S. W. Sloan

Discussion of “Quasi-Static Rheology of Granular Media Using the Static DEM” by J. Meng, J. Huang, D. Sheng, and S. W. Sloan

Discussion of “Quasi-Static Rheology of Granular Media Using the Static DEM” by J. Meng, J. Huang, D. Sheng, and S. W. Sloan

Quasi-Static Rheology of Granular Media Using the Static DEM

Quasi-Static Rheology of Granular Media Using the Static DEM