A frictional soliton controls the resistance law of shear-thickening suspensions in pipes.

Pipe flows are commonly found in nature and industry as an effective mean of transporting fluids. They are primarily characterized by their resistance law, which relates the mean flow rate to the driving pressure gradient. Since Poiseuille and Hagen, various flow regimes and fluid rheologies have been investigated, but the behavior of shear-thickening suspensions, which jam above a critical shear stress, remains poorly understood despite important applications (e.

Nonlocal Effects Reflect the Jamming Criticality in Frictionless Granular Flows Down Inclines.

The jamming transition is accompanied by a rich phenomenology such as hysteresis or nonlocal effects that is still not well understood. Here, we experimentally investigate a model frictionless granular layer flowing down an inclined plane as a way to disentangle generic collective effects from those arising from frictional interactions. We find that thin frictionless granular layers are devoid of hysteresis of the avalanche angle, yet the layer stability increases as it gets thinner.

Revealing the frictional transition in shear-thickening suspensions.

Shear thickening in dense particulate suspensions was recently proposed to be driven by the activation of friction above an onset stress needed to overcome repulsive forces between particles. Testing this scenario represents a major challenge because classical rheological approaches do not provide access to the frictional properties of suspensions. Here we adopt a different strategy inspired by pressure-imposed configurations in granular flows that specifically gives access to this information.

Irreversibility and chaos: role of lubrication interactions in sheared suspensions.

We investigate non-Brownian particles suspended in a periodic shear-flow using simulations. Following Metzger and Butler [Phys. Rev.

Forward problem study of an effective medium model for ultrasound blood characterization.

The structure factor model (SFM) is a scattering model developed to simulate the backscattering coefficient (BSC) of aggregated red blood cells (RBCs). However, the SFM can hardly be implemented to estimate the structural aggregate parameters in the framework of an inverse problem formulation. A scattering model called the effective medium theory combined with the SFM (EMTSFM) is thus proposed to approximate the SFM.

Irreversibility and chaos: role of long-range hydrodynamic interactions in sheared suspensions.

Non-Brownian particles suspended in an oscillatory shear flow are studied numerically. In these systems it is often assumed that chaos (due to the long-range nature of the hydrodynamic interaction between particles) plus noise (contact or roughness) lead to irreversible behavior. However, we demonstrate that the long-range hydrodynamic interactions are not a source, nor even a magnifier, of irreversibility when coupled with nonhydrodynamic interactions.

Particle-pressure-induced self-filtration in concentrated suspensions.

Gravity-driven flow of concentrated suspensions (solid volume fraction ϕ>0.50) of non-brownian spherical particles through a channel contraction at low Reynolds number is studied experimentally. The abrupt change in the flow area at the contraction forms distinct shear-rate regions having different fluid pressures, which are related to the concept of particle pressure.

Large-scale streamers in the sedimentation of a dilute fiber suspension.

We experimentally characterize structures formed during the sedimentation of rigid fibers of high aspect ratio at small Reynolds number using particle image velocimetry. Measurements show the existence of large-scale streamers during early stages of the sedimentation process, consistent with previously published theory and numerical simulations. At longer times, the cell-wide inhomogeneities evolve into smaller-scale streamers.