Numerical Study on the Distribution of Rodlike Particles in Laminar Flows of Power Law Fluids Past a Cylinder

The contraction/expansion laminar flow containing rodlike particles in power-law fluid is studied numerically when the particles are in a dilute phase. The fluid velocity vector and streamline of flow are given at the finite Reynolds number (Re) region. The effects of Re, power index n and particle aspect ratio beta on the spatial and orientation distributions of particles are analyzed. The results showed that for the shear-thickening fluid, particles are dispersed in the whole area in the contraction flow, while more particles are gathered near the two walls in the expansion flow. The spatial distribution of particles with small beta is more regular. Beta has a significant, n has a moderate, but Re has a small impact on the spatial distribution of particles in the contraction and expansion flow. In the case of large Re, most particles are oriented in the flow direction. The particles near the wall show obvious orientation along the flow direction. In shear-thickening fluid, when the flow changes from contraction to expansion, the orientation distribution of particles becomes more dispersed; while in shear-thinning fluid, the opposite is true. More particles orient to the flow direction in expansion flow than that in contraction flow. The particles with a large beta tend to align with the flow direction more obviously. Re, n and beta have great influence on the orientation distribution of particles in the contraction and expansion flow. Whether the particles initially located at the inlet can bypass the cylinder depends on the transverse position and initial orientation of the particles at the inlet. The number of particles with theta(0) = 90 degrees bypassing the cylinder is the largest, followed by theta(0) = 45 degrees and theta(0) = 0 degrees. The conclusions obtained in this paper have reference value for practical engineering applications.

Automated summary

This paper numerically studies the contraction/expansion laminar flow with rodlike particles in power-law fluid at a dilute phase. The effects of Reynolds number (Re), power index (n), and particle aspect ratio (beta) on the spatial and orientation distributions of particles are analyzed. The results show that particle distribution is influenced by the fluid type, with more dispersion in contraction flow for shear-thickening fluid and more gathering near the walls in expansion flow. The orientation distribution of particles is affected by Re, n, and beta, with larger beta leading to a more obvious alignment with the flow direction.