Efficient transport of sand or cuttings is of great importance in oil and gas industry and the fluid velocity in these processes should be high enough to keep particles continuously moving along the pipe. This minimum fluid velocity below which particles deposit, defined as the critical velocity, depends on various factors including flow regime, particle size, particle concentration, phase velocities and fluid viscosity. The objective of this study is to investigate the effect of parameters such as particle size and liquid viscosity on solid particle transport in horizontal pipelines using Computational Fluid Dynamics (CFD) simulations and validate the numerical model predictions with experimental data.

CFD simulations have been conducted with a commercially available software, ANSYS-FLUENT. Eulerian model with k-ω SST turbulence closure model is used to simulate the fluid flow while particles are tracked as the Lagrangian phase. In these simulations eddy interaction model is included to consider the effect of flow turbulence on the particle track. The simulations are created for 0.05 m pipe diameter with 4 m length. The simulations are initialized at relatively high fluid velocity, which is gradually reduced until the particle velocity drops below the acceptable critical velocity.

The CFD simulation results are validated with experimental data from literature, Najmi (2015) and Najmi et al. (2016) for two particle sizes and multiple liquid viscosities. It was observed that the critical velocity values for liquid flows are comparable with CFD simulation results. The simulation results show that depending on the flow regimes (laminar or turbulent) and particle size, the critical velocity can demonstrate similar trend with carrier liquid viscosity as that of the experimental data. Also the CFD simulations and experiment results are compared with three models currently used in industry, namely Oroskar and Turian (1980) model, Salama (2000) model and Danielson (2007) model.

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