CoSy lunch: Shear-thinning, shear-thickening, jamming and negative compressibility in dense suspensions

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Abstract: Dense suspensions can be found in our everyday life, ranging from tooth-paste to cement mixtures. They are two-phase systems where a solid phase is immersed in a fluid phase with a large content of solid material (and henceforth referred to as dense). Their resistance to flow (i.e. viscosity) is well-known to increase with the amount of solid material it contains. How this relation looks like for dilute suspensions was already solved by Einstein in the beginning of the last century. Dense suspensions are, however, far from the ideal dilute case and shows more complex flow behaviors. They can shear-thicken, shear-thin, jam and even show negative compressibility. I will discuss recent progress in our understanding of these complex flow phenomena found in these fairly simple systems.