Reynolds-averaged modeling of turbulent flows of power-law fluids

Gavrilov, A. A.; Rudyak, V. Ya.

doi:10.1016/j.jnnfm.2015.11.006

Cited by 46 publications

(45 citation statements)

References 22 publications

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“…One now solves the above equations to obtain an ensemble-averaged velocity and pressure field, u and p. If the molecular viscosity is not constant but is a function of the shear rate, the Reynolds decomposition of the diffusive term will result in an ensemble-averaged and a fluctuating value of the effective viscosity [16]. Upon including this term, Equation (14) reads…”

Section: Computational Fluid Dynamics (Cfd) and Non-newtonian Fluidsmentioning

confidence: 99%

“…Further, the closure proposed by Gavrilov and Rudyak [16] assumes that the fluctuations in effective viscosity (η ) are smaller than the ensemble-averaged viscosity. In a turbulent flow, the turbulent viscosity brings about a higher amount of dissipation as compared to the molecular (or effective) viscosity [24].…”

Section: Computational Fluid Dynamics (Cfd) and Non-newtonian Fluidsmentioning

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: Computational Fluid Dynamics (Cfd) and Non-newtonian Fluidsmentioning

confidence: 99%

Section: Computational Fluid Dynamics (Cfd) and Non-newtonian Fluidsmentioning

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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“…Since CWSs can exhibit non-Newtonian properties in certain cases, the non-Newtonian flows were modeled using the approach from [23][24], where a medium is considered a non-linear viscous liquid with the introduction of effective viscosity ) ( 1    , which normally depends on the shear rate.…”

Section: Mathematical Model Of Droplet Breakupmentioning

confidence: 99%

Study of the Weber number impact on secondary breakup of droplets of coal water slurries containing petrochemicals

Минаков

Shebeleva

Стрижак

et al. 2019

Fuel

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The research presents the numerical modeling findings of the secondary breakup of droplets of coal water slurries containing petrochemicals (CWSP). The modeling method of the secondary droplet breakup is based on the VOF method for interface resolution, LES model for describing turbulence, and the technology of adapted dynamic grids. We have established the droplet breakup modes depending on the Weber number varying from 7 to 212. We have also examined the structure of the flow behind droplets. We have tested the numerical method, and the results are in good agreement with the existing experiments.

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“…These models require an additional transport equation for ε in order to close the system. Therefore, in the case of threedimensional flow, additional 7 partial differential equations are added to the system of Reynolds equations [28]. This project uses the two-equation SST k-ω turbulence model.…”

Section: Calculation Of Flow Parametersmentioning

confidence: 99%

Analysis of the Project of Innovative Floating Turbine

Tomporowski

Al-Zubiedy

Flizikowski

et al. 2019

Polish Maritime Research

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The design of a floating, innovative device for river water aeration and conversion of mechanical energy to electrical energy required the analysis of a number of geometrical and dynamic features. Such an analysis may be carried out on the basis of existing methods of numerical fluid mechanics. Models of pressures, forces and torques characteristic for the conversion of watercourse energy were developed for two basic concepts of innovation. These pressures, forces and torques were calculated, designed, and experimentally determined for the variable geometric form and dimensions of the designed working elements of the innovative roller-blade turbine rotor.

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Reynolds-averaged modeling of turbulent flows of power-law fluids

Cited by 46 publications

References 22 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

Study of the Weber number impact on secondary breakup of droplets of coal water slurries containing petrochemicals

Analysis of the Project of Innovative Floating Turbine

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