A wall boundary condition for the simulation of a turbulent non-Newtonian domestic slurry in pipes

Autor: Jules B. van Lier, Francois Clemens, Adithya Krishnan Thota Radhakrishnan, Dhruv Mehta
Jazyk: angličtina
Rok vydání: 2018
Předmět:
lcsh:Hydraulic engineering
Geography
Planning and Development

Herschel–Bulkley fluid
02 engineering and technology
Aquatic Science
Computational fluid dynamics
Non-Newtonian
Reynolds-averaged Navier-Stokes
01 natural sciences
Biochemistry
Law of the wall
010305 fluids & plasmas
Physics::Fluid Dynamics
symbols.namesake
lcsh:Water supply for domestic and industrial purposes
020401 chemical engineering
Reynolds-averaged Navier–Stokes
lcsh:TC1-978
0103 physical sciences
Herschel–Bulkley
Newtonian fluid
Shear stress
0204 chemical engineering
Water Science and Technology
Pipe flow
lcsh:TD201-500
business.industry
Reynolds number
Herschel-Bulkley
Mechanics
Non-Newtonian fluid
Domestic slurry
domestic slurry
pipe flow
non-Newtonian
symbols
Reynolds-averaged Navier–Stokes equations
business
Geology
Zdroj: Water, 10(2)
Water; Volume 10; Issue 2; Pages: 124
Water, Vol 10, Iss 2, p 124 (2018)
ISSN: 2073-4441
Popis: 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.
Databáze: OpenAIRE