Mechanical behavior of biological sludge in flow

This study aims to provide additional knowledge about the mechanical behavior of the flow of biological sludges. For this purpose, model fluids, i.e. bentonite suspensions, have been investigated. The experimental study considers the evolution of the rheological parameters of bentonite muds in unidirectional flows inside a circular pipe where velocity profiles and pressure were measured in stationary regime. We study the velocity profiles. The axial velocity profile is characterized by a plug zone around the axis of the duct and a shear zone at the wall. The effect of singularities in the breakdown of suspensions was highlighted. The measurement of viscosity shows shear-thinning nature of the sludge. The study of friction shows a trend inversely proportional to the Reynolds number in laminar flow and a transition to turbulence for Re-exp approximate to 2050.