On the role of polymer–particle interactions in elasto-inertial dissipation in Taylor–Couette flow

Abstract

Abstract Content of image described in text. Complex suspensions composed of solid particles dispersed in non-Newtonian liquid matrices are ubiquitous in environmental and industrial processes, where their nonlinear rheological response directly impacts the efficiency and predictability of momentum, heat and mass transfer. Here, we experimentally investigate the interplay between non-colloidal spherical particles and high-molecular-weight polymer chains in the canonical Taylor–Couette flow, a configuration where recent experiments have revealed the emergence of an elasto-inertial dissipation (EID) behaviour whose underlying mechanisms remain unclear. Using a polyacrylamide Boger fluid loaded with particles at varying concentrations, we perform systematic rheological measurements and long-duration shear experiments to quantify viscosity, elasticity and the degradation dynamics. Torque monitoring shows that particle addition accelerates polymer chain scission and reduces the asymptotic viscosity. Ramp-up protocols reveal torque-drop behaviour characteristic of EID, which can be qualitatively reproduced by a cumulative-shear degradation model derived from steady-shear data. However, the inability of this model to capture the strong dependence on particle volume fraction indicates that additional semi-dilute particle–polymer interaction mechanisms are at play. In particular, by relating average interparticle distance to the maximum polymer chain extension, we identify a critical particle volume fraction ( upper Phi asymptotically equals 4 percent sign Φ≃4% $\varPhi \simeq 4\,\%$ ) coinciding with the observed transition from elasto-inertial turbulence (EIT) to EID. These findings show, that while polymer degradation is a key contributor to dissipation, confinement of stretched chains between particles is a more likely mechanism for the suppression of EIT. This dual influence of degradation and particle–polymer interactions offers new insight into rheo-hydrodynamic transitions in complex suspensions and their implications for industrial applications.