Pseudo elastoinertial turbulence in viscoelastic fluids

Turbulence induced by the bubbly swarms (pseudo turbulence) has been extensively studied due to its relevance in industrial applications. Despite the prevalence of non-Newtonian fluids in many of these applications, most studies focused on the Newtonian continuous phase. We investigate the homogeneous bubble swarm rising at a moderate Reynolds number in a viscoelastic shear-thinning fluid by varying the gas volume fraction. The liquid velocity fluctuations were measured in the wake behind the bubble swarm using particle image velocimetry (PIV). We observe a significant change from the classical energy spectral decay with the wave number, $k^{-3}$, by gradually increasing the Weissenberg number. Further, experiments were conducted in a shear thinning inelastic fluid to quantify the effects of elasticity. The work provides insights into the emerging research of elastoinertial turbulence (EIT) recently observed in viscoelastic fluids.