Numerical investigation on two-degree-of-freedom vortex-induced vibration of a circular cylinder in power-law fluids

• Published in: Journal of non-Newtonian fluid mechanics Vol. 292; p. 104535
• Main Authors: Ashouri, Ali, Izadpanah, Ehsan, Hekmat, Mohamad Hamed, Amini, Yasser
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.06.2021; Elsevier BV
• Subjects: Aerodynamic coefficients; Circular cylinder; Circular cylinders; Coefficient of friction; Computational fluid dynamics; Degrees of freedom; Displacement; Fluid flow; Mass-spring-damper systems; Newtonian fluids; Non-Newtonian fluid; Power law; Power-law index; Resonant frequencies; Reynolds number; Shear thickening (liquids); Shear thinning (liquids); Thickening; Trajectories; Transverse oscillation; Two-degree-of-freedom; Viscosity; Vortex shedding; Vortex shedding pattern; Vortex-induced vibration; Vortex-induced vibrations; Circular cylinder; Two-degree-of-freedom; Power-law index; Vortex shedding pattern; Vortex-induced vibration; Non-Newtonian fluid
• ISSN: 0377-0257; 1873-2631
• DOI: 10.1016/j.jnnfm.2021.104535

•The influence of the power-law fluid on the 2DOF vortex-induced vibration is studied.•The effects of the power-law index on the vibration characteristics are remarkable.•Different vortex shedding modes are observed for the shear-thinning fluid. In this paper, the two-degree-of-freedom (2DOF) vortex-induced vibration (VIV) of a circular cylinder in shear-thinning and shear-thickening non-Newtonian power-law fluids are numerically investigated. A virtual spring-damper-mass system is employed to predict the VIV of the cylinder. A comprehensive analysis is conducted to study the influence of dimensionless parameters, including reduced velocity (3≤Ur≤12) and power-law index (0.4≤n≤1.8) at a low Reynolds number (Re=150) and low mass ratio (mr=2) on the vortex shedding pattern, displacement frequencies, local apparent viscosity, friction coefficient, trajectories of the displacements, drag and lift coefficients, and the cylinder displacements. The results indicate that the apparent viscosity and the natural frequency of the system have a substantial effect on the characteristics of the VIV of the cylinder. By changing the values of the reduced velocity, various vortex shedding patterns such as 2S, 2P, S + P, and complex modes are observed for the non- Newtonian fluids, and several motion trajectories other than the typical figure “8″ are analyzed. By increasing the power-law index, the range of the lock-in region and the corresponding reduced velocity of the maximum transverse vibration amplitude change.