科研之友
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摘要
Dense granular flows exhibit large clusters of grains rotating in correlated fashions. We present a method to identify and quantify such granular vortices, based on the circulation of velocity fluctuations around closed curves. Here, the method is applied on physical experiments of two-dimensional granular flows in the Stadium Shear Device geometry. Results illustrate how the method is capable to capture the positions, sizes, velocities and life-times of individual vortices. The method should be useful for many purposes, including: (1) complementing existing ways for defining typical correlation lengths in granular systems; (2) studying the kinematics behind the superior efficiency of granular systems to transfer of mass, heat and momentum when compared with other fluids; and (3) characterising vortices in other particulate fluid systems such as suspensions, emulsions and foams, which exhibit similar velocity patterns.
- 出版日期2015-4
