Dynamic self-assembly of staggered oblate particle train in a square duct

The dynamic self-assembly of staggered oblate particle train in a three-dimensional square duct is numerically investigated via the multiple-relaxation-time lattice Boltzmann method. The present study aims to explore the effect of the Reynolds number (Re), average length fraction (〈L〉), and particle aspect ratio (AR) on the entire migration process, distribution pattern, and mean axial interparticle spacing (d /D). Herein, it should be noted that AR is varied by changing the polar radius of the oblate particle, whereas the corresponding equatorial radius, i.e., the rotational diameter, keeps unchanged. The whole forming process of the staggered oblate particle train consists of the inertial migration toward the face equilibrium positions and the dynamic self-assembly in the streamwise direction. Present results indicate that the distribution pattern and (d/D) of the staggered oblate particle train are significantly dependent on 〈L〉 and Re. Within the parameter range studied, continuous pattern, with all inter-particle distances being identical, preferentially appears in high 〈L〉 and large Re for moderate 〈L〉. As 〈L〉 increases, the corresponding (d/D) ≈ 1/〈L〉 decreases. Discontinuous pattern, with varying inter-particle distances, occurs in low 〈L〉 and small Re for moderate 〈L〉, where (d/D) is mainly determined by Re. The data show that (d/D) increases linearly with Re. Furthermore, at 〈L〉 = 0.4, particles with AR = 0.5, 0.75, 1 all self-organize into staggered train with the discontinuous pattern for Re ≤ 40 with a non-monotonic dependence of (d/D) on AR, while they are in the continuous pattern for Re ≥ 60. Nevertheless, due to the same rotational diameter, particles with different AR yield almost the same face equilibrium positions.[Figure not available: see fulltext.]