Bottom wall friction coefficients on the dynamic properties of sheared granular flows

In this study, we used a two-dimensional annular shear cell to systematically investigate the dynamic properties of granular flow when it is subjected to varying bottom wall friction coefficients. A particle tracking method and image processing technology were employed to measure tangential velocity, slip velocity, local solid fraction, and granular temperature. The results demonstrated that the bottom wall friction coefficient played a crucial role in determining the dynamic properties of sheared granular flows, indicating that slip velocity is larger when a rougher bottom wall is applied. The results also indicated that the tangential velocity and granular temperature were reduced when the roughness of the bottom wall increased because of the strong frictional effect, which caused a larger dissipation of energy. The average granular temperature increased linearly when the solid fraction at each specific bottom wall friction coefficient increased.