Experimental study of low inertia vortex rings in shear-thinning fluids

Omar Bentata (1) , Dominique Anne-Archard (2) , Pierre Brancher (2)

1 USTO MB - Université des sciences et de la Technologie d'Oran Mohamed Boudiaf [Oran]
2 IMFT - Institut de mécanique des fluides de Toulouse

The present work investigates experimentally the dynamics of vortex rings in shear-thinning fluids at low generalized Reynolds numbers, with a focus on the range from 300 down to 30. The experimental apparatus consists of a vertical cylinder-piston system with the lower part immersed in a tank filled with the liquid. Particle image velocimetry is used to analyze the influence of the non-Newtonian nature of the fluid on the generation, propagation, and eventual dissipation of vortex rings. The results show that shear-thinning controls the generation phase, whereas the vortex ring subsequent evolution is independent of the power-law index. In particular, it is found that the final dissipation stage is characterized by a flow dynamics which tends ultimately to a regime at a constant viscosity corresponding to the Newtonian plateau. This reveals the role of the Carreau number and of the Reynolds number based on this specific viscosity as relevant control parameters for this last stage.

Mots clés: Vortex ring; Non-Newtonian Fluid Mechanics; Shear-thinning fluids; Vortex dynamic; Rheological properties; Laminar flows; Velocimetry

Domaines: Mécanique des fluides [physics.class-ph]

Omar Bentata, Dominique Anne-Archard, Pierre Brancher. Experimental study of low inertia vortex rings in shear-thinning fluids. Physics of Fluids, 2018, 30 (11), pp.1-10. ⟨10.1063/1.5048841⟩. ⟨hal-01958621⟩