A note on the effect of ultrasonic waves on droplets rising in Newtonian and non-Newtonian fluids

Fuentes, Adrien; Madera, Rebeca Cedeño; Moreno, Luzviminda B.; Camacho, Roberto Zenit; Iniesta, Baltasar Mena; Brito, Octavio Manero

doi:10.15406/fmrij.2018.02.00035

Cited by 2 publications

(2 citation statements)

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“…Shear-thinning fluids exist in a wide range of industrial processes such as air lubrication (Bobade et al 2017;Selway, Chan & Stokes 2017), aeration (Samaras et al 2014), airlift pumps, food processing (McClements 2004) and blood pumps (Moyers-Gonzalez, Owens & Fang 2009). Dispersions, such as drops (Ohta et al 2003), bubbles (Premlata et al 2017) and particles are often found in shear-thinning fluid systems.…”

Section: Introductionmentioning

confidence: 99%

“…The pulsation, oscillation and acoustic excitation increase the speed of a bubble (Stein & Buggisch 2000;Iwata et al 2008;Karapetsas et al 2019), drop (Mendoza-Fuentes et al 2018) or particle (Iwamuro, Watamura & Sugiyama 2019), and significantly augment the rate of heat transfer in shear-thinning fluids (Gupta, Patel & Chhabra 2020Mishra, Patel & Chhabra 2020;Mishra & Chhabra 2021). Qualitatively, the cause is attributed to the reduction in the effective viscosity.…”

Section: Introductionmentioning

confidence: 99%

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Drag force on an oscillatory spherical bubble in shear‐thinning fluid

2023

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Power-law shear-thinning fluid motions induced by a translating spherical bubble with sinusoidal oscillation at a high frequency are numerically studied. We focus on reducing the time-averaged drag force $D$ on the bubble owing to the oscillation-enhanced shear-thinning effect. Under the assumption of negligible convection, the unsteady Stokes equation is directly solved in a finite-difference manner over a wide parameter space of the dimensionless oscillation amplitude $A$ (corresponding to the oscillatory-to-translational velocity ratio) and the power-law index $n$ of the viscosity. The results show that, for small amplitude ( $A\ll 1$ ), the drag reduction ratio $1-D/D_0$ (here, $D_0$ is $D$ with no oscillation) is proportional to $A^2$ . In contrast, for large amplitude ( $A \gg 1$ ), the drag ratio $D/D_0$ is proportional to $A^{n-1}$ , revealing a power-law behaviour. In the case of $A \gg 1$ for a strong shear-thinning fluid with small $n$ , the square of the vorticity over the entire domain is much smaller than that of the shear rate, and thus the bulk flow may be regarded as irrotational. To provide a fundamental perspective on the drag reduction mechanism, a theoretical model is proposed based on potential theory, and demonstrated to well capture the power-law relation between $D/D_0$ and $A$ .

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Drag force on an oscillatory spherical bubble in shear‐thinning fluid

2023

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The Influence of Ultrasound Irradiation on Falling Sphere in Pseudo-Plastic Fluid

Iwamuro¹,

Watamura²,

Sugiyama³

2019

JAPANESE JOURNAL OF MULTIPHASE FLOW

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Ultrasound effects on the motion of a falling sphere in water (i.e. Newtonian fluid) and in PolyAcrylAmide (PAA) solution (i.e. non-Newtonian shear-thinning fluid) are experimentally investigated via an image processing technique. The falling speed in water is confirmed to be almost irrespective of the frequency or amplitude in the applied ultrasound, while that in PAA solution is found to be higher with increasing the ultrasound intensity. In consideration of pseudo-plastic factors estimated by various velocity and length scales involved in the system, we consider that the mechanism to enhance the falling speed has the influence of viscosity in the acoustic boundary layer and its thickness.

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A note on the effect of ultrasonic waves on droplets rising in Newtonian and non-Newtonian fluids

Cited by 2 publications

References 0 publications

Drag force on an oscillatory spherical bubble in shear‐thinning fluid

Drag force on an oscillatory spherical bubble in shear‐thinning fluid

The Influence of Ultrasound Irradiation on Falling Sphere in Pseudo-Plastic Fluid

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