Yield–stress shear thinning and shear thickening fluid flows in deformable channels

Garg, Ashish; Prasad, Pranjal

doi:10.1088/1402-4896/ad2898

Cited by 6 publications

(4 citation statements)

References 40 publications

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“…The results gathered from these simulations collectively support the idea that even in highly narrow CNTs with a diameter as small as 1.66 nm, the flow of water behaves following the slip-modified Hagen-Poiseuille relation. Interestingly, the actual flow rates they observed were higher than what we would expect based on the traditional no-slip Hagen-Poiseuille relation [29][30][31], where water sticks to the tube walls. However, their theory failed to support the claims made by Majumder et al [15] and Holt [32,33] in their previous studies, where they suggested that water behaves very differently in these nanotubes.…”

Section: Introductionmentioning

confidence: 79%

An empirical experimental observations and MD simulation data-based model for the material properties of confined fluids in nano/Angstrom size tubes

Garg,

Bishnoi

2024

Nano Ex.

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The transport of fluids in nano/Angstrom-sized pores has gotten much attention because of its potential uses in nanotechnology, energy storage, and healthcare sectors. Understanding the distinct material properties of fluids in such close confinement is critical and dictate the fluid's behavior in determining flow dynamics, transport processes, and, ultimately, the performance of nanoscale devices. Remarkably, many researchers observed that the size of the geometry, such as confining nanotube diameter, exerts a profound and intriguing influence on the material properties, including on the critical parameters such as density, viscosity, and slip length. Many researchers tried to model viscosity $\eta$, density $\rho$, and slip $\lambda$ using various models with multiple dependencies on the tube-diameter. It is somewhat confusing and tough to decide which model is appropriate and can be incorporated in simulation. In this paper, we propose a simple single equation for each nanoconfined material property such as for density $\displaystyle \rho(D)/\rho_o = a+ b/(D-c)^n$, viscosity $\displaystyle \eta(D)/\eta_o = a+ b/(D-c)^n$, and the slip length $\lambda(D) = \lambda_1~D~e^{-n~D}+ \lambda_o$ (where $a,~b,~c,~n,~\lambda_1,~\lambda_o$ are the free fitting parameters). We model a wealth of previous experimental and MD simulation data from the literature using our proposed model for each material property of nanoconfined fluids. Our single proposed equation effectively captures and models all the data, even though many different models have been employed in literature to describe the same material property. Our proposed model exhibits exceptional agreement with multiple independent datasets from the experimental observations and MD simulations. Additionally, the model possesses continuity and continuous derivative, so that it is well-suited for simulations. The proposed models also obey the far boundary conditions, i.e., when tube-diameter $D \implies \infty$, the material properties approaches bulk properties of fluid. Because of models' simplicity, smooth, and generic nature, it holds promise to apply in simulations to design/optimize nanoscale-devices.

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Section: Introductionmentioning

confidence: 79%

An empirical experimental observations and MD simulation data-based model for the material properties of confined fluids in nano/Angstrom size tubes

Garg,

Bishnoi

2024

Nano Ex.

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“…Their MD simulations consistently support the notion that water flow within nanochannels adheres to the slip-modified Hagen-Poiseuille relation. This finding is particularly interesting because it suggests higher flow rates compared to those predicted by the traditional no-slip Hagen-Poiseuille relation [16][17][18], which assumes water molecules stick to the channel walls. Also, Israelachvili [13] experimentally calculated the viscosity of tetradecane and water between two mica sheets placed at distances lower than 50 Å and proposed that the viscosity of water/tetradecane can be calculated using…”

Section: Introductionmentioning

confidence: 82%

Heuristic Modeling of Material Properties in Nano/Angstrom-Scale Channels: Integrating Experimental Observations and MD Simulations

Mishra,

Garg

2024

Preprint

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Nanofluidics, the study of fluids confined within nanoscale channels, holds immense potential for various applications. However, these fluids exhibit unique properties (density, viscosity, and slip length) that deviate from their bulk counterparts and critically impact flow dynamics. Understanding and characterizing these properties is essential for designing efficient nanofluidic systems. Traditionally, numerous models, often complex and disparate, have been used to describe these properties. The current abundance of models makes selecting the most suitable one for numerical simulations a challenging task. In this paper, we propose a simpler, unified framework: a single power-law model for each property such as for density $\displaystyle \rho(H)/\rho_o = 1+ m_1~H^{-n_1}$, viscosity $\displaystyle \eta(H)/\eta_o = 1+ m_2~H^{-n_2}$, and the slip length $\lambda(H) = \lambda_o + m_3~H^{-n_3}$ (where $m_1, m_2, m_3, n_1, n_2, n_3, \lambda_o$ are the free fitting parameters). This model effectively captures data from experiments and simulations, even where existing literature employed diverse models. A key advantage of our model lies in its mathematical properties. Continuity and a continuous derivative ensure seamless implementation into numerical simulations and theoretical predictions, leading to more understable, stable and accurate results. Additionally, the model adheres to physical principles, predicting convergence to bulk properties as channel size increases. Further this proposed unified power-law model for density, viscosity, and slip length compared to existing exponential models, offers flexibility where it captures non-linear relationships and diverse data curvatures. Interpretability with clear physical meaning for parameters. Adaptability to combine with other functions for complex phenomena. Simplicity for easy parameter estimation, model interpretation, and computations. Robustness and less sensitive to outliers and noise in data and with fewer parameters to easy relate to underlying physics and scaling-laws. Hence proposed model's simplicity, smoothness, physical validity and generality make it a significant heuristic model for efficient design and optimization of nanoscale devices using theory and simulations across a wide range of applications.

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“…Also, the shear stress τ xz is acting along the negative x direction on both the surfaces DD ′ C ′ C and AA ′ B ′ B. Dropping the xz notation from the stress, the force balance can be written as [30,31]…”

Section: D Planar Modelmentioning

confidence: 99%

The channel flow of a real shear thickening fluid using the Lattice Boltzmann Simulation and the Theoretical Model

Vishal,

Garg,

Sarkar

et al. 2024

Preprint

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Understanding a real shear-thickening fluid (STF) flowing through channel is essential in developing soft body armour applications. A real shear thickening fluid has a combination of parts-wise Newtonian, shear thinning and shear thickening regions in the viscosity-shear rate plot. The Lattice Boltzmann method (LBM), a mesoscopic simulation, is employed in a D2Q9 framework to study the flow characteristics of a real shear thickening fluid. To validate the results, we compared the numerical and analytical results obtained for fluid flow with a combination of power-law fluids with shear thickening and shear thinning behaviour, which are characterized by different power-law indexes. The effect of stress and strain rate on fluid flow has been studied. Next, we have also extended the above model to see the characteristics of the flow properties of a real shear thickening fluid having three distinct regions of Newtonian, shear thinning, and shear thickening in the viscosity-shear rate plot and discussed the results using the Lattice Boltzmann method (LBM) and with a theoretical model. We find that for the low shear rates, the Newtonian flow rate dominates, and as we keep increasing the shear rate through increasing, the thinning behaviors start to dominate, followed by the thickening phenomenon of the flow. We also find that initially, the flow begins with the Newtonian flow, and as we increase the channel height, the thinning flow starts to dominate, and for larger height channels, the thickening flow of real STF dominates.

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Yield–stress shear thinning and shear thickening fluid flows in deformable channels

Cited by 6 publications

References 40 publications

An empirical experimental observations and MD simulation data-based model for the material properties of confined fluids in nano/Angstrom size tubes

An empirical experimental observations and MD simulation data-based model for the material properties of confined fluids in nano/Angstrom size tubes

Heuristic Modeling of Material Properties in Nano/Angstrom-Scale Channels: Integrating Experimental Observations and MD Simulations

The channel flow of a real shear thickening fluid using the Lattice Boltzmann Simulation and the Theoretical Model

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