An engineering model of solids diffusivity in hydraulic conveying

An engineering model of solids diffusivity in a turbulent pipeline slurry flow is developed. While the model assumes that the liquid eddy diffusivity is uniform across a pipe the non-uniform distribution of solids diffusivity is obtained by analyzing the dependence of the turbulence kinetic energy transferred from liquid to particles on solids concentration. The turbulence kinetic energy transferred to particles is determined as the turbulence kinetic energy calculated for slurry minus the energy spent on the liquid-solids viscous friction due to turbulence induced liquid-solids velocity difference. The two empirical coefficients of the equation of the solids diffusivity have been identified from the measured solids concentration profiles. The numerical study has shown that the model accurately predicts the slurry concentration distribution in the wide range of flow parameters. The predictive capability of the developed model is much better that that of the conventional model of the solids diffusivity.