Experimental study of turbulence decay in dense suspensions using index-matched hydrogel particles

Zhang, K.; Rival, David E.

doi:10.1063/1.5031767

Cited by 13 publications

(7 citation statements)

References 40 publications

(36 reference statements)

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“…The current study extends its analysis of depletion efficiency to dilute and dense suspensions by using a refractive index matching technique (Wiederseiner et al 2010). Recently, studies using super-absorbent hydrogel beads of various diameters have demonstrated turbulence attenuation and vortex formation dynamics in dense suspensions with volume fractions up to 25 % (Zhang & Rival 2018;Baker & Coletti 2019;Zhang & Rival 2020). However, much is still unknown about the contribution of the suspended phase in the entrainment process of pulsatile recirculating flows.…”

Section: Steady Versus Pulsatile Flowsmentioning

confidence: 79%

“…The mean inter-particle spacing, normalized by the bead diameter, is l p /d p ≈ 2.3, 1.9 and 1.5 for the Φ = 5 %, 10 % and 20 % suspensions, respectively, where l p is the centre-to-centre distance between hydrogel beads and l p /d p ≤ 2 for dense suspensions (Kryuchkov 2001). The settling velocity of the hydrogel beads has previously been measured at approximately 0.6 ± 0.3 mm s −1 (Zhang & Rival 2018) and is very low when compared to the convective speeds of the system. Furthermore, the concentration of beads in the current tested suspensions is sufficiently high that these particles cannot be considered to move (settle) in isolation of one another.…”

Section: Hydrogel Beads -Making a Dense Suspensionmentioning

confidence: 99%

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On the lifespan of recirculating suspensions with pulsatile flow

Jeronimo

Rival

2021

J. Fluid Mech.

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A Lagrangian analysis is performed to measure the rate at which recirculating fluid is replaced (depleted) in pulsatile flows. Based on this approach, we then investigate how depletion is affected in dense suspensions. Experiments are conducted for pure liquid as well as suspensions with volume fractions of $\varPhi =5\,\%$ , 10 % and 20 %. Using Lagrangian tracking and pathline extension techniques, the depletion of the recirculation region is quantified via the trajectories of individual fluid parcels exiting the domain. Pulsatile flows with varying concentrations of hydrogel beads, up to a volume fraction of 20 %, are compared at mean Reynolds numbers of $Re=4800$ , 9600 and 14 400, while the Strouhal number ( $St=0.04$ , 0.08 and 0.15) and amplitude ratio ( $\lambda =0.25$ , 0.50 and 0.95) are systematically varied. A so-called ‘depletion efficiency’ is calculated for each test case, which is shown to increase with increasing Strouhal number and amplitude ratio. For most pulsatile cases, periodic vortex formation significantly increases depletion efficiency through enhanced entrainment of recirculating fluid. Conversely, low-amplitude pulsatile flows are dominated by Kelvin–Helmholtz instabilities, which do not penetrate into the recirculation region, and thus their depletion efficiency is markedly lower as a result. The efficiency trends and depletion mechanisms remain virtually unchanged between the pure liquid and each of the suspension concentrations under almost all flow conditions, which forms an unexpected conclusion. The only exception is for low-amplitude and steady flows, where increasing the suspension volume fraction is shown to suppress fluid transport across the shear layer, which in turn slows depletion and decreases the overall depletion efficiency.

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Section: Steady Versus Pulsatile Flowsmentioning

confidence: 79%

Section: Hydrogel Beads -Making a Dense Suspensionmentioning

confidence: 99%

On the lifespan of recirculating suspensions with pulsatile flow

Jeronimo

Rival

2021

J. Fluid Mech.

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“…The aforementioned PIV measurement technique that renders suspensions optically transparent was first demonstrated by Zhang & Rival (2018). In that study, a velocity uncertainty of 0.33 pixels was obtained for measurements taken through approximately 85 particle–fluid interfaces.…”

Section: Experiments Set-upmentioning

confidence: 99%

“…Additionally, we compare the dynamics of vortex rings in dense suspensions with those formed in pure water at low Reynolds numbers (Palacios-Morales & Zenit 2013), since the effective viscosity typically increases in suspensions. We implement refractive index matched hydrogel particles to produce optically transparent suspensions (Zhang & Rival 2018), which enables the use of time-resolved particle image velocimetry (PIV) measurements to quantify the velocity and vorticity fields of the liquid phase. This method has also been successfully applied to measure the solid and liquid phases of confined vortex rings simultaneously in suspensions using shake-the-box measurement techniques (Zhang, Jeronimo & Rival 2019).…”

Section: Introductionmentioning

confidence: 99%

On the dynamics of unconfined and confined vortex rings in dense suspensions

Zhang

Rival

2020

J. Fluid Mech.

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“…Recent progress in numerical algorithms and computer technology enables researchers to examine the behavior of individual particles in great detail in suspensions even at high solid volume fractions (Kazerooni et al 2017). Nonetheless, only a few experimental studies address the individual particle dynamics in suspensions beyond the dilute regime by means of optical measurement techniques such as Particle Image Velocimetry (PIV) (Zade et al 2018(Zade et al , 2019Zhang and Rival 2018) or a combination of PIV and 2D Particle Tracking Velocimetry (PTV) (Baker and Coletti 2019). Optical measurement techniques have been proven to be reliable tools for investigating fluid flow problems with high spatial and temporal resolutions.…”

Section: Introductionmentioning

confidence: 99%

On the calibration of Astigmatism particle tracking velocimetry for suspensions of different volume fractions

Brockmann

Hussong

2021

Exp Fluids

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In the present study, we demonstrate for the first time how Astigmatism Particle Tracking Velocimetry (APTV) can be utilized to measure suspensions dynamics. Measurements were successfully performed in monodisperse, refractive index matched suspensions of up to a volume fraction of $$\varPhi =19.9\%$$ Φ = 19.9 % . For this, a small percentage ($$\varPhi <0.01\%$$ Φ < 0.01 % ) of the particles is labeled with fluorescent dye acting as tracers for the particle tracking procedure. Calibration results show, that a slight deviation of the refractive index of liquid and particles leads to a strong shape change of the calibration curve with respect to the unladen case. This effect becomes more severe along the channel height. To compensate the shape change of the calibration curves the interpolation technique developed by Brockmann et al. (Exp Fluids 61(2): 67, 2020) is adapted. Using this technique, the interpolation procedure is applied to suspensions with different volume fractions of $$\varPhi <0.01\%$$ Φ < 0.01 % , $$\varPhi =4.73\%$$ Φ = 4.73 % , $$\varPhi =9.04\%$$ Φ = 9.04 % , $$\varPhi =12.97\%$$ Φ = 12.97 % , $$\varPhi =16.58\%$$ Φ = 16.58 % and $$\varPhi =19.9\%$$ Φ = 19.9 % . To determine the effect of volume fraction on the performance of the method, the depth reconstruction error $$\sigma _z$$ σ z and the measurement volume depth $$\varDelta z$$ Δ z , obtained in different calibration measurements, are estimated. Here, a relative position reconstruction accuracy of $$\sigma _z$$ σ z /$$\varDelta z$$ Δ z = 0.90% and $$\sigma _z$$ σ z /$$\varDelta z$$ Δ z = 2.53% is achieved for labeled calibration particles in dilute ($$\varPhi <0.01\%$$ Φ < 0.01 % ) and semi-dilute ($$\varPhi \approx 19.9\%$$ Φ ≈ 19.9 % ) suspensions, respectively. The measurement technique is validated for a laminar flow in a straight rectangular channel with a cross-sectional area of 2.55 × 30 mm$$^2$$ 2 . Uncertainties of 1.39% and 3.34% for the in-plane and 9.04% and 22.57% for the out-of-plane velocity with respect to the maximum streamwise velocity are achieved, at solid volume fractions of $$\varPhi <0.01\%$$ Φ < 0.01 % and $$\varPhi =19.9\%$$ Φ = 19.9 % , respectively.

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Experimental study of turbulence decay in dense suspensions using index-matched hydrogel particles

Cited by 13 publications

References 40 publications

On the lifespan of recirculating suspensions with pulsatile flow

On the lifespan of recirculating suspensions with pulsatile flow

On the dynamics of unconfined and confined vortex rings in dense suspensions

On the calibration of Astigmatism particle tracking velocimetry for suspensions of different volume fractions

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