Convection behavior of ellipsoidal particles in a quasi-two-dimensional bed under vertical vibration.

Ellipsoidal particles are anisotropic in shape. Production practice often involves the distribution and convection of ellipsoidal particles under external excitation. However, few studies have focused on convection in ellipsoidal particles. Herein, we experimentally investigated the convection behavior of ellipsoidal particles in a two-dimensional bed under vertical vibration. Several patterns were observed at the dimensionless vibration acceleration (Г) values of 1–6 within the frequency (ƒ) range of 12–70 Hz. The displacement vectors of single roll, asymmetrical double rolls and symmetrical double rolls were drawn. At fixed Г , the system changed from global convection to local convection with increased ƒ. To describe convection intensity, the expansion of bed and the volume fraction of convection region were proposed. Results showed that higher Г or lower ƒ led to stronger convection intensity. The relationship between the pattern and input energy distribution was further discussed. The arrangement of the ellipsoidal-particle long axis along the streamline or at an angle was observed under weak vibration. Two necessary conditions for this phenomenon were observed, namely, nonspherical particles and low input energy. Unlabelled Image • The phase diagram of ellipsoidal particle convection is divided into seven regions. • Bed expansion and volume fraction are used to characterize convection intensity. • The relationship between pattern and input energy distribution is presented. • Non-spherical particles and low input energy are necessary for ordered structure. [ABSTRACT FROM AUTHOR]