Drag of Tandem Spheroids in Power-Law Fluids at Moderate Reynolds Numbers

The relative motion between a power-law fluid and two tandem spheroid particles was investigated numerically. The field equations that govern this problem were solved using a commercial computational-fluid-dynamics-based solver. The semi-implicit method for pressure-linked equations (SIMPLE) algorithm and the quadratic upstream interpolation for convective kinematics (QUICK) scheme for convective terms were used. The solver was thoroughly benchmarked through domain and grid studies. Further, extensive new results are presented for the following ranges of conditions: Reynolds number (Re), 1–200; particle aspect ratio (e), 0.5–2; power-law index (n), 0.4–1.6; and interparticle distance (S), 2–5. The main focus of this work was to report the effects of these parameters on the streamlines, surface viscosity, and drag coefficients of the tandem particles. The dependence of the average drag coefficient on the power-law index and Reynolds number had a crossover Reynolds number that was found to be a strong function of the particle aspect ratio and the interparticle distance. Below this crossover Reynolds number, the average drag coefficient increased with decreasing power-law index, whereas for Reynolds numbers greater than the crossover Reynolds number, the average drag coefficient decreased with decreasing power-law index.