Abstract

Adding rigid particles in a fluid is known to change its properties, which might be a strategy to control the behavior of complex fluids. However, despite its long research history and its practical relevance both in industrial applications and in geophysical problems, the mechanics of suspensions in the dense regime remains poorly understood. In this talk, we will discuss experimental results obtained for suspensions of rigid spheres and rigid fibres in a newtonian fluid, with a special attention to the very dense regime close to the jamming transition. The case of suspensions in a complex fluid (particles in a yield stress fluid and in a shear thickening fluid) will also be discussed, showing how empirical constitutive laws can be proposed from the knowledge of the rheology of newtonian suspensions and the rheology of the suspending fluid.