Dynamics and rheology of elastic particles in an extensional flow

We investigate the dynamics and rheology of elastic particles in a viscous extensional flow under Stokes flow conditions by means of the large deformation method developed by Gao, Hu & Ponte Castaneda (J. Fluid M e c h., vol. 687, 2011, pp. 209-237). The particles are assumed to be homogeneous, incompressible and neo-Hookean solids. When subjected to extensional flow, an initially ellipsoidal (elliptical) elastic particle stretches and rotates simultaneously, tending to deform into a stable ellipsoidal shape with the initial major axis aligned with the extension direction. However, the steady-state solutions may not exist when the particle stiffness is lower than a certain critical value. By using the solution of a single particle, the macroscopic rheological properties are evaluated for a dilute suspension of elastic particles under extension. Similar to some polymer blends, softer particles lead to a larger extensional viscosity for the suspension.