Numerical simulations were performed to study the particle shape effect on the particle-scale diffusion and mixing behavior in the mixer driven by the rotating paddles. Four shapes of particles, the sphere, the prolate spheroid, the oblate spheroid, and the cube, are simulated. Velocities, flow blockages, and diffusion of particles are analyzed. The mixing index is applied to quantitatively evaluate the mixing. Numerical results show that the circumferential velocity in the above-paddle region is much greater than in the paddle region. Compared to other shapes, the cubic particles have less movement in low velocity and more in high velocity. The cubic shape, rather than the ellipsoidal shape of different aspect ratios, plays a non-negligible role in flow blockage. For particle diffusion, the mean square displacement (MSD) varies linearly with time for the sphere, the prolate, and the oblate spheroids. The average diffusion coefficient is about 6.5 × 10^-5 m²/s. In contrast, the MSD of the cubes is greater than the other shapes, and a sub-diffusion phenomenon is observed. The mixing index increases with time and reaches approximately a steady value of 0.9 after 3.0 s. Because of the different particle–wall interactions, the mixing indices of the cube, the prolate, and the oblate spheroids in the mixer are less than those of the sphere. Finally, radial mixing and axial mixing are evaluated by the eight kinds of mixing functions. These mixing functions and their time-averaged values show that the cubic particle has significantly different features of mixing. Its radial mixing is stronger than other kinds of shapes. Also, the cube’ axial mixing upward is weaker whereas the mixing downward is the strongest.

通过数值模拟来研究颗粒形状对旋转桨叶驱动的混合器中颗粒尺度扩散和混合行为的影响。模拟了四种形状的颗粒：球体、长椭球体、扁椭球体和立方体。分析粒子的速度、流动阻塞和扩散。混合指数用于定量评价混合情况。数值结果表明，桨叶上方区域的圆周速度远大于桨叶区域的圆周速度。与其他形状相比，立方体颗粒在低速时运动较少，在高速时运动较多。立方体形状，而不是不同长径比的椭圆体形状，在流动阻塞中起着不可忽视的作用。对于粒子扩散，球体、长球体和扁球体的均方位移 (MSD) 随时间线性变化。平均扩散系数约为6.5×10 ^-5 m ² /s。相反，立方体的 MSD 大于其他形状，并且观察到亚扩散现象。混合指数随着时间的推移而增加，并在 3.0 秒后达到大约 0.9 的稳定值。由于颗粒与壁的相互作用不同，立方体、长椭球体和扁球体在混合器中的混合指数小于球体。最后通过八种混合函数对径向混合和轴向混合进行了评价。这些混合函数及其时间平均值表明立方粒子具有显着不同的混合特征。其径向混合力比其他形状更强。此外，立方体向上的轴向混合较弱，而向下的混合最强。