Numerical simulation of flow of a shear-thinning Carreau fluid over a transversely oscillating cylinder

Alam, Irshad; Raj, Apurva; Khan, Piru Mohan; Kumar, Subrata; Roy, Somnath

doi:10.1017/jfm.2021.485

Cited by 25 publications

(18 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This finding implies that in a self-excited VIV case, only 2S shedding would be observed in the wake. Alam et al (2021) also show that the vortices in a shear-thinning fluid have a stronger asymmetric pattern with higher levels of unsteadiness while departing from the lock-in mode.…”

Section: Introductionmentioning

confidence: 76%

“…Shear-thinning effects reduce the formation length in the wake of a fixed cylinder, and shear-thickening effects increase the formation length (Coelho & Pinho 2003a,b, 2004Lashgari et al 2012;Bailoor et al 2019;Şahin and Atalık 2019). Shear-thinning effects reduce the drag coefficient (at least for low Reynolds numbers Re ≤ 300) (Lashgari et al 2012;Bailoor et al 2019;Alam et al 2021) and intensify the magnitude of the vorticity in the region close to the cylinder, due to the reduced shear stress associated with the shear-thinning effects that occur very close to the cylinder (Lashgari et al 2012). In these studies on shear-thinning and shear-thickening fluid, Şahin and Atalık (2019) use a power-law fluid model in which viscosity, η, is proportional to the shear rate, γ , to the power n − 1, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Hopkins & de Bruyn (2019) showed that the effective viscosity, determined by averaging the viscosity around the circumference of the cylinder and over one period of oscillations, depends significantly on the driving frequency, and it reaches the minimum at a resonant frequency. Alam et al (2021) studied the vortex dynamics in the locked-in mode and non-locked-in mode of a transversely oscillating cylinder in shear-thinning fluids at Re = 100, where Re is defined based on the zero-shear-rate viscosity. They showed that the vortex separation length is shorter in the shear-thinning fluids compared with the Newtonian fluid due to reduced viscous diffusion near the vortices in the wake.…”

Section: Introductionmentioning

confidence: 99%

“…2019; Alam et al. 2021) and intensify the magnitude of the vorticity in the region close to the cylinder, due to the reduced shear stress associated with the shear-thinning effects that occur very close to the cylinder (Lashgari et al. 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Alam et al. (2021) studied the vortex dynamics in the locked-in mode and non-locked-in mode of a transversely oscillating cylinder in shear-thinning fluids at , where is defined based on the zero-shear-rate viscosity. They showed that the vortex separation length is shorter in the shear-thinning fluids compared with the Newtonian fluid due to reduced viscous diffusion near the vortices in the wake.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Vortex-induced vibrations of a cylinder in inelastic shear-thinning and shear-thickening fluids

2022

View full text Add to dashboard Cite

Vortex-induced vibrations (VIV) of a cylinder in a Newtonian fluid is a model problem in fluid–structure interactions and has been studied extensively. In this work, we study the influence of shear-thinning and shear-thickening fluids on the VIV response of a one-degree-of-freedom flexibly-mounted cylinder. We consider a system with a mass ratio of $m^*=2$ and zero structural damping in shear-thinning and shear-thickening power-law fluids at $Re_0 = 15$ and $Re_0 = 200$ , respectively, defined based on the zero-shear-rate viscosity of the fluids. We investigate how the VIV amplitude and frequency, flow forces, and the vorticity contours change as the reduced velocity, $U^*$ , and fluid's time constant, $\lambda$ , change. When the results are compared based on $Re_0$ , shear-thinning fluids enhance the oscillations while shear-thickening fluids suppress them. If, however, we define a characteristic Reynolds number, $Re_{char}$ , based on a viscosity evaluated at the characteristic shear rate, $\dot {\gamma } = U/D$ , then at a constant $Re_{char}$ , the amplitude of response stays very similar for the shear-thinning, shear-thickening and Newtonian fluids. Despite this similarity, the observed far wake is different: shear thinning amplifies the generation of vorticity and reduces the extent of the wake, whereas shear thickening limits the generation of vorticity and extends the wake. Our findings show that the local apparent viscosity observed close to the cylinder placed in shear-thinning or shear-thickening fluids governs the VIV response of the cylinder.

show abstract

Section: Introductionmentioning

confidence: 76%