Turbulent coarse-particle non-Newtonian suspension flow in a pipe

Abstract

High concentration tailings suspension is attracting increasingly more attention due to its environmental and economic benefits. The interaction between non-Newtonian carrier and coarse particles in high concentration suspensions is still poorly understood, particularly in a turbulent regime. This paper presents a DNS-DEM model for weakly turbulent coarse-particle non-Newtonian suspensions. Matching experiments were conducted for validation. The predicted mixture flow rates and concentration profiles were in good agreement with experiments and mostly less than 10% difference. The validated model was applied to investigate how the carrier rheology affect the flow behaviour. The flows all displayed stratification and particles were able to settle in the weakly turbulent regime. Turbulence in the lower portion of the pipe was damped with the presence of concentrated particles thus became ineffective in re-suspending the particles. A stronger coupling between the fluid and particles was found for flow with a higher yield stress, however this beneficial effect was compromised by the presence of weaker turbulence. The combined effect contributed to only slightly improved solids suspension in flow with a higher yield stress. The DNS-DEM model can be used to quantitatively determine the influence of different flow parameters on pipeline performance under a wide range of operating conditions.