Mixed‐Regime Slurries in Pipelines. I: Mechanistic Model

A generalized mechanistic model is presented for the hydraulic transport of mixed‐regime slurries in pipelines. Mixed‐regime slurries are defined as those two phase (solids‐liquid) mixtures containing a wide range of particle sizes, the distribution of which generally lies between pseudo‐homogeneous slow‐settling slurries and heterogeneous rapid‐settling slurries. The mechanistic model presented herein consists of three components—a vehicle portion, a suspended portion, and a bed‐load portion. Each component of the particle size distribution is analyzed to determine its contribution to the fraction of vehicle load, suspended load, and bed load. The vehicle and suspended load components are combined to determine the wall shear above the bed load interface. This wall shear is converted to a force and added to the bed load resisting force to determine the total friction head loss gradient along the pipe. The incipient sliding bed condition is found by equating the bed load resisting force to the driving force on the bed load. The mechanistic model is compared to experimental results from laboratory pipelines. Each component of the particle size distribution is analyzed to determine its contribution to the fraction of vehicle load, suspended load, and bed load.