A DNS Investigation of the Effect of Yield Stress for Turbulent Non-Newtonian Suspension Flow in Open Channels

Abstract

The use of fixed-shape open channels in industrial processes is common in the mineral processing industry. With lack of fundamental understanding about the mechanisms involved in how a turbulent flow of a non-Newtonian carrier fluid transports suspension particles, direct numerical simulation may come into the research as a validation tool. Direct numerical simulation (DNS) of the turbulent flow of non-Newtonian fluids in an open channel is modeled using a spectral element-Fourier method. The simulation of a yield-pseudoplastic fluid using the Herschel-Bulkley model agrees qualitatively with experimental results from field measurements of mineral tailing slurries. The simulation results over-predict the flow velocity by approximately 40% for the cases considered, however, the source of the discrepancy is difficult to ascertain. The effect of variation in yield stress, flow behavior index, and assumed flow depth are investigated and used to assess the sensitivity of the flow to these physical parameters. This methodology is seen to be useful in designing and optimizing the transport of slurries in open channels.

Turbulent channel flow of an elastoviscoplastic fluid

“…Despite the numerous studies performed to analyze viscoelastic turbulent flows, much less attention has been given to viscoplastic and elastoviscoplastic fluids. Indeed, very few numerical works exist on fully turbulent flows of an elastoviscoplastic fluid, and to the best of our knowledge the only direct numerical simulations of the effect of a yield stress on a turbulent non-Newtonian flow were performed by Rudman & Blackburn (2006) and Guang et al (2011). These authors simulated a yield-pseudoplastic fluid using the Herschel-Bulkley model and compared the results with experimental measurements.…”

Effect of finite Weissenberg number on turbulent channel flows of an elastoviscoplastic fluid

“…In addition, many earlier direct numerical simulation studies addressed the turbulence in Bingham pseudoplastic fluids (obtained by regularising the Bingham model by a large viscosity) (Rudman & Blackburn 2006; Guang et al. 2011; Zhu et al. 2020), and their shear-thinning version, regularised Herschel–Bulkley fluids by Rudman et al.…”