Modulation of elasto-inertial transitions in Taylor–Couette flow by small particles

Particle suspensions in non-Newtonian liquid matrices are frequently encountered in nature and industrial applications. We here study the Taylor–Couette flow (TCF) of semidilute spherical particle suspensions (volume fraction $\leq 0.1$ ) in viscoelastic, constant-viscosity liquids (Boger fluids). We describe the influence of particle load on various flow transitions encountered in TCF of such fluids, and on the nature of these transitions. Particle addition is found to delay the onset of first- and second-order transitions, thus stabilising laminar flows. It also renders them hysteretic, suggesting an effect on the nature of bifurcations. The transition to elasto-inertial turbulence (EIT) is shown to be delayed by the presence of particles, and the features of EIT altered, with preserved spatio-temporal large scales. These results imply that particle loading and viscoelasticity, which are known to destabilise the flow when considered separately, can on the other hand compete with one another and ultimately stabilise the flow when considered together.

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Scalable Exfoliation of Bulk MoS2 to Single- and Few-Layers Using Toroidal Taylor Vortices

Nanomaterials ◽

10.3390/nano8080587 ◽

2018 ◽

Vol 8 (8) ◽

pp. 587 ◽

Cited By ~ 10

Author(s):

Vishakha Kaushik ◽

Shunhe Wu ◽

Hoyoung Jang ◽

Je Kang ◽

Kyunghoon Kim ◽

...

Keyword(s):

Couette Flow ◽

Flow Reactor ◽

Batch Process ◽

Industrial Applications ◽

Shear Stresses ◽

Mos2 Nanosheets ◽

Taylor Vortices ◽

Taylor Couette ◽

Bulk Mos2 ◽

Taylor Couette Flow

The production of a large amount of high-quality transition metal dichalcogenides is critical for their use in industrial applications. Here, we demonstrate the scalable exfoliation of bulk molybdenum disulfide (MoS2) powders into single- or few-layer nanosheets using the Taylor-Couette flow. The toroidal Taylor vortices generated in the Taylor-Couette flow provide efficient mixing and high shear stresses on the surfaces of materials, resulting in a more efficient exfoliation of the layered materials. The bulk MoS2 powders dispersed in N-methyl-2-pyrrolidone (NMP) were exfoliated with the Taylor-Couette flow by varying the process parameters, including the initial concentration of MoS2 in the NMP, rotation speed of the reactor, reaction time, and temperature. With a batch process at an optimal condition, half of the exfoliated MoS2 nanosheets were thinner than ~3 nm, corresponding to single to ~4 layers. The spectroscopic and microscopic analysis revealed that the exfoliated MoS2 nanosheets contained the same quality as the bulk powders without any contamination or modification. Furthermore, the continuous exfoliation of MoS2 was demonstrated by the Taylor-Couette flow reactor, which produced an exfoliated MoS2 solution with a concentration of ~0.102 mg/mL. This technique is a promising way for the scalable production of single- or few-layer MoS2 nanosheets without using hazardous intercalation materials.

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Mode competition in modulated Taylor–Couette flow

Journal of Fluid Mechanics ◽

10.1017/s0022112008000748 ◽

2008 ◽

Vol 601 ◽

pp. 381-406 ◽

Cited By ~ 11

Author(s):

M. AVILA ◽

M. J. BELISLE ◽

J. M. LOPEZ ◽

F. MARQUES ◽

W. S. SARIC

Keyword(s):

Couette Flow ◽

Physical Experiment ◽

Mode Competition ◽

Taylor Vortex ◽

Coexistence Region ◽

Narrow Region ◽

Taylor Couette ◽

Spatio Temporal ◽

Temporal Symmetry ◽

Taylor Couette Flow

The effects of harmonically oscillating the inner cylinder about a zero mean rotation in a Taylor–Couette flow are investigated experimentally and numerically. The resulting time-modulated circular Couette flow possesses a Z2 spatio-temporal symmetry which gives rise to two distinct modulated Taylor vortex flows. These flows are initiated at synchronous bifurcations, have the same spatial symmetries, but are characterized by different spatio-temporal symmetries and axial wavenumber. Mode competition between these two states has been investigated in the region where they bifurcate simultaneously. In the idealized numerical model, the two flows have been found to coexist and be stable in a narrow region of parameter space. However, in the physical experiment, neither state has been observed in the coexistence region. Instead, we observe noise-sustained flows with irregular time-dependent axial wavenumber. Movies are available with the online version of the paper.

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Effect of inertial migration of particles on flow transitions of a suspension Taylor-Couette flow

Physical Review Fluids ◽

10.1103/physrevfluids.5.114303 ◽

2020 ◽

Vol 5 (11) ◽

Author(s):

Lina Baroudi ◽

Madhu V. Majji ◽

Jeffrey F. Morris

Keyword(s):

Couette Flow ◽

Inertial Migration ◽

Taylor Couette ◽

Flow Transitions ◽

Taylor Couette Flow

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Numerical study of heat flow characteristics of turbulent Taylor-Couette flow in slit wall mode

Journal of Engineering Research ◽

10.36909/jer.9955 ◽

2021 ◽

Vol 9 ◽

Author(s):

Dong Liu ◽

◽

Mohammed Mohammedsalih ◽

Amponsah-Gyenin Nana Kofi ◽

Shi-cheng Ding ◽

...

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Couette Flow ◽

Numerical Study ◽

Flow Characteristics ◽

Simulation Method ◽

Industrial Applications ◽

Small Scale ◽

Taylor Couette ◽

Taylor Couette Flow

Heat transfer enhancement is by far an important component in the design of numerous industrial applications of Taylor-Couette flow including electric motors and particularly rotating machinery. To optimize the performances of these machines, superior knowledge of the fluid flow is vital to better estimate the heat transfer distribution. This study will specifically consider the effect the slit number and width possess on the distribution of turbulent Taylor-Couette flow and the resulting heat transfer correlation in the annulus of two concentric cylinders under varying conditions. A numerical simulation method is intended for the study using varying slit structure parameters of widths (2.5 ≤ w ≤ 7.5) mm and fitted with 6, 9 and 12 number of slits. The slit effect is then investigated under both isotherm and non-isotherm conditions considering the interactions between fluid flow regions in the mainstream area and the annulus. The small-scale vortex that appears in the annulus region improves the heat transferability between the fluid in the annulus and the main region as well as the heat transfer performance of the model with a gradual increase in Reynolds number.

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