The Effect of Shear-Thinning Rheology on the Dynamics and Pressure Distribution of a Single Rigid Ellipsoidal Particle in Viscous Fluid Flow

TL;DR

This study investigates how shear-thinning rheology influences the motion and pressure distribution of a rigid ellipsoidal particle in viscous flow, revealing significant modifications to particle behavior and surface pressure compared to Newtonian fluids.

Contribution

The paper introduces a finite element analysis model for ellipsoidal particles in shear-thinning fluids and extends Jeffery's model to complex flow regimes, enhancing understanding of fluid-structure interactions.

Findings

Shear-thinning reduces surface pressure on the particle.

Particle trajectories are significantly altered by shear-thinning rheology.

The FEA model aligns with Jeffery's analytical results for Newtonian fluids.

Abstract

This paper evaluates the behavior of a single rigid ellipsoidal particle suspended in homogenous viscous flow with a power-law Generalized Newtonian Fluid (GNF) rheology using a custom-built finite element analysis (FEA) simulation. The combined effects of the shear-thinning fluid rheology, the particle aspect ratio, the initial particle orientation and the shear-extensional rate factor in various homogenous flow regimes on the particle's dynamics and surface pressure evolution are investigated. The shear-thinning fluid behavior was found to modify the particle's trajectory and alter the particle's kinematic response. Moreover, the pressure distribution over the particle's surface is significantly reduced by the shear-thinning fluid rheology. The FEA model is validated by comparing results of the Newtonian case with results obtained from the well-known Jefferys analytical model. Furthermore, Jefferys model is extended to define the particle's trajectory in a special class of homogenous Newtonian flows with combined extension and shear rate components typically found in axisymmetric nozzle flow contractions. The findings provide an improved understanding of key transport phenomenon related to physical processes involving fluid-structure interaction (FSI) such as that which occurs within the flow-field developed during material extrusion-deposition additive manufacturing of fiber reinforced polymeric composites. These results provide insight into important microstructural formations within the print beads.