Flow of solid-liquid mixtures in inclined pipes

The prediction of the flow characteristics of solid-liquid mixtures in inclined pipes has much practical importance, since long distance pipelines are bound to contain inclined sections. The three-layer model of Doron and Barnea (1993) was extended to account for the angle of inclination, which is expected to affect both the pressure drop and the limit deposit velocity. The extended model reproduces satisfactorily new experimental data as well as data of previous investigators. The additional effect of the gravitational force induces higher pressure gradients together with higher limit deposit velocity as the pipe's upward tilt is increased. For downwards inclination, the limit deposit velocity decreases drastically, and the pressure drop is reduced, since for downflow gravitation acts as a driving force.