Author(s): Jules B. Van Lier; Francois H. L. R. Clemens; Dhruv Mehta; Adithya Krishnan Thota Radhakrishnan

Linked Author(s):

Keywords: Domestic slurry; Herschel–Bulkley; Non-Newtonian; Pipe flow; Reynolds-averaged Navier–Stokes; Urban hydraulics

Abstract: This article concerns the turbulent flow of Herschel–Bulkley slurries through circular horizontal pipes; in particular, that of concentrated domestic slurry obtained upon separation of domestic waste water and reduction in the use of water for domestic purposes. Experiments with a rheologically equivalent clay (kaolin) slurry indicated a non-Newtonian behaviour of the Herschel–Bulkley type. A modified wall function was developed to enable the Reynolds-averaged Navier–Stokes simulation of Herschel–Bulkley slurries to estimate the wall shear stress. Despite the accuracy achieved, the use of Reynolds-averaged Navier–Stokes models for an entire waste water system is impractical. Therefore, this article assesses the accuracy of semi-empirical models in estimating frictional losses. It also discusses possible modifications of existing models to encompass Herschel–Bulkley behaviour. An evaluation suggests that most existing models deliver estimates of comparable accuracy; however, the probability of these estimates being reliable, while accounting for experimental errors in quantifying the actual frictional losses, is rather low.

DOI: https://doi.org/10.1080/00221686.2020.1744751

Year: 2021