Grease flow in an elbow channel

The final publication is available at Springer via http://dx.doi.org/10.1007/s11249-015-0469-6. The flow of lubricating greases in an elbow channel has been modeled and validated with velocity profiles from flow visualizations using micro-particle image velocimetry. The elbow geometry induces a non-symmetric distribution of shear stress throughout its cross section, as well as varying shear rates through the transition from the elbow inlet to the outlet. The flow has been modeled both for higher flow rates and for creep flow. The influence of the grease rheology and flow conditions to wall slip, shear banding and an observed stick-slip type of motion observed for low flow rates are presented. The effect on the flow of the applied pressure is also modeled showing that the flow is sensitive to the pressure in the angular (phi) direction of the elbow. For high pressures, it is shown that the flow is reversed adjacent to the elbow walls.