Pattern formations in particle laden drum flows and Taylor-Couette flows with co-rotating cylinders

In this work, previously undescribed particle patterns are reported for suspensions of initially uniform dispersed non-Brownian particles in completely filled rotating drum flows and in completely filled co-rotating Taylor-Couette (TC) flows under the influence of gravity. Extending previous studies, a thorough phase mapping is performed for the drum flow with a low viscosity working liquid (1 cP) and d(p) approximate to 500 mu m glass beads at a solid volume fraction of Phi = 0:11%. A wide range of cylinder radii is covered (R-o = 7-145 mm), and for the first time, a phase mapping is performed for a co-rotating TC flow for varying radius ratios. A total of 55 different geometrical combinations have been considered within the experiments. For both the drum and the TC flow, a series of clearly distinguishable patterns are observed including three different types of axial band structures as well as azimuthal band structures. The experiments indicate that in the case of the drum flow, the pattern formation strongly depends on the outer cylinder diameter, whereas in the case of the Taylor-Couette flow, the gap height has a strong effect on the pattern formation. In the TC case, it is observed that the wavelength of all band patterns shows a striking dependence on the cylinder radius and the curvature of the system.

Automated summary

In this study, previously unreported particle patterns are observed in completely filled rotating drum flows and completely filled co-rotating Taylor-Couette flows for suspensions of initially uniform dispersed non-Brownian particles under the influence of gravity. The experiments include thorough phase mapping for both drum flow and Taylor-Couette flow, and a total of 55 different geometrical combinations are considered. The results show that the pattern formation in drum flow is strongly dependent on the outer cylinder diameter, while in Taylor-Couette flow, the gap height has a strong effect on the pattern formation. Additionally, the wavelength of all band patterns in Taylor-Couette flow is found to be dependent on the cylinder radius and system curvature.