Experimental investigation of torque hysteresis behaviour of Taylor–Couette Flow

Abstract

This paper describes the hysteresis in the torque for Taylor-Couette flow in the turbulent flow regime for different shear Reynolds numbers, aspect ratios and boundary conditions. The hysteresis increases with decreasing shear Reynolds number and becomes more pronounced as the aspect ratio is increased from 22 to 88. Measurements conducted in two different Taylor-Couette set-ups depict the effect of the flow conditions at the ends of the cylinders on the flow hysteresis by showing reversed hysteresis behaviour. In addition, the flow structure in the different branches of the hysteresis loop was investigated by means of stereoscopic particle image velocimetry. The results show that the dominant flow structures differ in shape and magnitude depending on the branch of the hysteresis loop. Hence, it can be concluded that the geometry could have an effect on the hysteresis behaviour of turbulent Taylor-Couette flow, but its occurrence is related to a genuine change in the flow dynamics.

Particle-laden Taylor–Couette flows: higher-order transitions and evidence for azimuthally localized wavy vortices

“…As a consequence, the dynamic/kinematic viscosity of the fluid may undergo significant changes. Previous studies in the same facility have sought solutions such as ensuring that the temperature did not vary by more than 0.5 • C (Tokgoz et al 2012), or by running the system for a few hours prior to the measurements, ensuring a stable temperature thereafter (Gul, Elsinga & Westerweel 2018). Such measures were not applicable for the current investigation due to the nature of the experimental protocol and, thus, an ad hoc approach to estimate the varying temperature throughout the experiments is adopted (similar to Greidanus et al 2015;Benschop et al 2018).…”

Taylor–Couette flow of polymer solutions with shear-thinning and viscoelastic rheology

“…Taylor–Couette flow occurs between two concentric cylinders, one or both of which is rotating, and has been of interest to the fluids community, rheologists, process engineers and mathematicians over the past century (Taylor 1923; Donnelly 1991). This is in part motivated by the fact that, in spite of its simple configuration, Taylor–Couette flow of Newtonian fluids can yield a vast array of complex dynamics, including a wide variety of steady and unsteady flow states (Coles 1965; Andereck, Liu & Swinney 1986), mode competition (Dutcher & Muller 2009), chaos (Akonur & Lueptow 2003) and transition to turbulence (Grossmann, Lohse & Sun 2016; Gul, Elsinga & Westerweel 2018). In the relatively simple case in which the outer cylinder is fixed, the system can be characterised using only the Reynolds number where and are the fluid density and dynamic viscosity, respectively, is the rotation speed, are the radius of the inner cylinder, and is the gap between the inner and outer cylinder radii ().…”

Large-scale structure transitions in turbulent Taylor–Couette flow

“…It is interesting to note that the Taylor vortices were also associated with torque hysteresis in TC flow (Huisman et al. 2014; Gul, Elsinga & Westerweel 2018). These observations support the view that the rolls contribute significantly to the torque.…”