Dynamical feature of particle dunes in Newtonian and shear-thinning flows: Relevance to hole-cleaning in pipe and annulus

Khatibi, Milad; Time, Rune W.; Shaibu, Rashid

doi:10.1016/j.ijmultiphaseflow.2017.10.015

Cited by 24 publications

(5 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many fluids display Newtonian flow behavior for sufficiently small rates γ. Liquid water in thermodynamic equilibrium is an example, with a viscosity that is known to be constant across several orders of magnitude of γ [16]. Much less is known, however, about the dynamical effects on the viscosity of water in its supercooled state.…”

mentioning

confidence: 99%

Non-Newtonian flow effects in supercooled water

Ribeiro

Koning

2020

Phys. Rev. Research

View full text Add to dashboard Cite

The viscosity of supercooled water has been a subject of intense study, in particular with respect to its temperature dependence. Much less is known, however, about the influence of dynamical effects on the viscosity in its supercooled state. Here we address this issue for the first time, using molecular dynamics simulations to investigate the shear-rate dependence of the viscosity of supercooled water as described by the TIP4P/Ice model. We show the existence of a distinct crossover from Newtonian to non-Newtonian behavior characterized by a power-law shear-thinning regime. The viscosity reduction is due to the decrease in the connectivity of the hydrogen-bond network. Moreover, the shear thinning intensifies as the degree of supercooling increases, whereas the crossover flow rate is approximately inversely proportional to the Newtonian viscosity. These results stimulate further investigation into possible fundamental relations between these nonequilibrium effects and the quasistatic Newtonian viscosity behavior of supercooled water.

show abstract

mentioning

confidence: 99%

Non-Newtonian flow effects in supercooled water

Ribeiro

Koning

2020

Phys. Rev. Research

View full text Add to dashboard Cite

show abstract

“…PVDF exhibits the lower storage modulus, while the modulus is increased with the doping of the ZnO‐G in PVDF. Contrary to this loss modulus is higher for the PVDF and less for the PNCs 62 . Hence, PNCs are more valuable perspectives for elastic applications than pure PVDF 63 .…”

Section: Resultsmentioning

confidence: 80%

Tuning of shear thickening behavior and elastic strength of polyvinylidene fluoride via doping of ZnO‐graphene

Goswami

Singh

Chamoli

et al. 2021

J of Applied Polymer Sci

View full text Add to dashboard Cite

ZnO rice like nonarchitects are grafted on the graphene carbon core via a rapid microwave synthesis route. The prepared grafted systems are characterized via XRD, SEM, RAMAN, and XPS to examined the structural and morphological parameters. Zinc oxide grafted graphene sheets (ZnO‐G) are further doped in β‐phase of polyvinylidene fluoride (PVDF) to prepare the polymer nanocomposites (PNCs) via mixed solvent approach (THF/DMF). β‐phase confirmation of PVDF PNCs is done by FTIR studies. It is observed that ZnO‐G filler enhances the β‐phase content in the PNCs. Non‐doped PVDF and PNCs are further studied for rheological behavior under the shear rate of 1–100 s−1. Doping of ZnO‐G dopant to the PVDF matrix changes its discontinuous shear thickening (DST) behavior to continues shear thickening behavior (CST). Hydrocluster formation and their interaction with the dopant could be the reason for this striking DST to CST behavioral change. Strain amplitude sweep (10−3% ‐10%) oscillatory test reveals that the PNCs shows extended linear viscoelastic region with high elastic modulus and lower viscous modulus. Effective shear thickening behavior and strong elastic strength of these PNCs present their candidature for various fields including mechanical and soft body armor applications.

show abstract

“…Here, Re is calculated using the following definition Re = ρVD i /μ, where V is the flow velocity. For all experiments, DI water (μ: 0.89 mPa•s and ρ: 996.89 kg/m 3 ) 21 and a water−glycerol mixture (47.5 v/v % glycerol, μ: viscosity: 6.85 mPa•s and ρ: 1140 kg/m 3 ) were employed. The 47.5 v/v % glycerol viscosity was measured with a dynamic shear rheometer (Kinexus Rotational Rheometer, Malvern Instruments) from a 0.01 to 100 shear rate at 25 °C.…”

Section: Experimental Methodsmentioning

confidence: 99%

Reduced Pressure Drop in Viscoelastic Polydimethylsiloxane Wall Channels

2021

View full text Add to dashboard Cite

Polydimethylsiloxane (PDMS) is an important viscoelastic material that finds applications in a large number of engineering systems, particularly lab-on-chip microfluidic devices built with a flexible substrate. Channels made of PDMS, used for transporting analytes, are integral to these applications. The PDMS viscoelastic nature can induce additional hydrodynamic contributions at the soft wall/fluid interface compared to rigid walls. In this research, we investigated the pressure drop within PDMS channels bounded by rigid tubes (cellulose tubes). The bulging effect of the PDMS was limited by the rigid tubes under flowing fluids. The PDMS viscoelasticity was modulated by changing the ratio of the base to the cross-linker from 10:1 to 35:1. We observed that the pressure drop of the flowing fluids within the channel decreased with the increased loss tangent of the PDMS in the examined laminar regime [Reynolds number (Re) ∼ 23–58.6 for water and Re ∼ 0.69–8.69 for glycerol solution]. The elastic PDMS 10:1 wall channels followed the classical Hagen Poiseuille’s equation, but the PDMS walls with lower cross-linker concentrations and thicker walls decreased pressure drops. The friction factor (f) for the PDMS channels with the two working fluids could be approximated as f = 47/Re. We provide a correlation between the pressure drop and PDMS viscoelasticity based on experimental findings. In the correlation, the loss tangent predominates; the larger the loss tangent, the smaller is the pressure drop. The research findings appear to be unexpected if only considering the energy dissipation of viscoelastic PDMS walls. We attributed the reduction in the pressure drop to a lubricating effect of the viscoelastic PDMS walls in the presence of the working fluids. Our results reveal the importance of the subtle diffusion of the residual oligomers and water from the bulk to the soft wall/fluid interface for the observed pressure drop in soft wall channels.

show abstract

Dynamical feature of particle dunes in Newtonian and shear-thinning flows: Relevance to hole-cleaning in pipe and annulus

Cited by 24 publications

References 27 publications

Non-Newtonian flow effects in supercooled water

Non-Newtonian flow effects in supercooled water

Tuning of shear thickening behavior and elastic strength of polyvinylidene fluoride via doping of ZnO‐graphene

Reduced Pressure Drop in Viscoelastic Polydimethylsiloxane Wall Channels

Contact Info

Product

Resources

About