Turbulent pipe flow of shear-thinning fluids

Rudman, Murray; Blackburn, Hugh Maurice; Graham, Lachlan; Pullum, Lionel

doi:10.1016/j.jnnfm.2004.02.006

Cited by 112 publications

(129 citation statements)

References 17 publications

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“…Because the viscosity of a non-Newtonian fluid changes with the local flow conditions, one cannot use the standard Reynolds number. Instead, Rudman et al [43] have proposed a Reynolds number based on the wall effective viscosity defined below. This viscosity can only be determined once the wall shear stress is known, and hence it serves only as a post-experimental (numerical) parameter.…”

Section: An Appropriate Reynolds Numbermentioning

confidence: 99%

“…Rudman et al [43] mentioned that this definition of the Reynolds number was more pertinent to the analysis of wall-bounded flows as it reflected the behaviour of Herschel-Bulkley fluids in the near-wall region, as compared to the more commonly used Metzner-Reed Reynolds numbers [44]. Re R is used while presenting the results of the simulations.…”

Section: An Appropriate Reynolds Numbermentioning

confidence: 99%

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A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes

Mehta

Radhakrishnan

Lier

et al. 2018

Water

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Abstract:The concentration (using a lesser amount of water) of domestic slurry promotes resource recovery (nutrients and biomass) while saving water. This article is aimed at developing numerical methods to support engineering processes such as the design and implementation of sewerage for concentrated domestic slurry. The current industrial standard for computational fluid dynamics-based analyses of turbulent flows is Reynolds-averaged Navier-Stokes (RANS) modelling. This is assisted by the wall function approach proposed by Launder and Spalding, which permits the use of under-refined grids near wall boundaries while simulating a wall-bounded flow. Most RANS models combined with wall functions have been successfully validated for turbulent flows of Newtonian fluids. However, our experiments suggest that concentrated domestic slurry shows a Herschel-Bulkley-type non-Newtonian behaviour. Attempts have been made to derive wall functions and turbulence closures for non-Newtonian fluids; however, the resulting laws or equations are either inconsistent across experiments or lack relevant experimental support. Pertinent to this study, laws or equations reported in literature are restricted to a class of non-Newtonian fluids called power law fluids, which, as compared to Herschel-Bulkley fluids, yield at any amount of applied stress. An equivalent law for Herschel-Bulkley fluids that require a minimum-yield stress to flow is yet to be reported in literature. This article presents a theoretically derived (with necessary approximations) law of the wall for Herschel-Bulkley fluids and implements it in a RANS solver using a specified shear approach. This results in a more accurate prediction of the wall shear stress experienced by a circular pipe with a turbulent Herschel-Bulkley fluid flowing through it. The numerical results are compared against data from our experiments and those reported in literature for a range of Reynolds numbers and rheological parameters that are relevant to the prediction of pressure losses in a sewerage transporting non-Newtonian domestic slurry. Nonetheless, the application of this boundary condition could be extended to areas such as chemical and food engineering, wherein turbulent non-Newtonian flows can be found.

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Section: An Appropriate Reynolds Numbermentioning

confidence: 99%

Section: An Appropriate Reynolds Numbermentioning

confidence: 99%

A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes

Mehta

Radhakrishnan

Lier

et al. 2018

Water

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“…There have been no general theories and/or mathematical and computational models to describe turbulent flow [2]. Instead, different analytical, semi-empirical and empirical correlations (explicit and implicit) have been proposed to predict friction factor under turbulent flow conditions [1].…”

Section: Introductionmentioning

confidence: 99%

Which Friction Factor Model Is the Best? A Comparative Analysis of Model Selection Criteria

Kamel¹,

Shaqlaih²,

Rozyyev³

2018

JEPE

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Abstract:The ongoing research for model choice and selection has generated a plethora of approaches. With such a wealth of methods, it can be difficult for a researcher to know what model selection approach is the proper way to proceed to select the appropriate model for prediction. The authors present an evaluation of various model selection criteria from decision-theoretic perspective using experimental data to define and recommend a criterion to select the best model. In this analysis, six of the most common selection criteria, nineteen friction factor correlations, and eight sets of experimental data are employed. The results show that while the use of the traditional correlation coefficient, R 2 is inappropriate, root mean square error, RMSE can be used to rank models, but does not give much insight on their accuracy. Other criteria such as correlation ratio, mean absolute error, and standard deviation are also evaluated. The AIC (Akaike Information Criterion) has shown its superiority to other selection criteria. The authors propose AIC as an alternative to use when fitting experimental data or evaluating existing correlations. Indeed, the AIC method is an information theory based, theoretically sound and stable. The paper presents a detailed discussion of the model selection criteria, their pros and cons, and how they can be utilized to allow proper comparison of different models for the best model to be inferred based on sound mathematical theory. In conclusion, model selection is an interesting problem and an innovative strategy to help alleviate similar challenges faced by the professionals in the oil and gas industry is introduced.

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“…The three specific rheological laws were different from that considered by B. C. Bell and K. S. Surana [7] for the same test case. M. Rudman et al [12,13] carried out direct numerical simulations to understand the turbulence flow of certain shear-thinning non-Newtonian fluids in a pipe. F. Zinani and S. Frey [14] analysed the fluid flow corresponding to the Casson rheological law in a 1:4 symmetric sudden expansion channel.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of the Transpose Diffusive Term for Viscoplastic-Type Non-Newtonian Fluid Flows Using a Collocated Variable Arrangement

Carmona

Lehmkuhl

Segarra

et al. 2015

Numerical Heat Transfer, Part B: Fundamentals

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The aim of this work is to delve into the numerical analysis of viscoplastic-type non-Newtonian fluid flows. Specifically, improvements in the spatial discretization schemes and the temporal integration methods have been proposed to overcome the numerical problems introduced by the transpose diffusive term and associated with the velocity field discontinuity, the artificial viscous diffusion and the transpose viscous coupling. The resulting knowledge may be useful, among many other things, to improve the corresponding numerical simulations and gain insight into the underlying physics of this class of non-Newtonian fluid flows.

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Turbulent pipe flow of shear-thinning fluids

Cited by 112 publications

References 17 publications

A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes

A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes

Which Friction Factor Model Is the Best? A Comparative Analysis of Model Selection Criteria

Numerical Analysis of the Transpose Diffusive Term for Viscoplastic-Type Non-Newtonian Fluid Flows Using a Collocated Variable Arrangement

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