Transient shear-jammed clusters in shear-thickening suspensions

Dense particulate suspensions demonstrate a significant increase in average viscosity beyond a material-specific critical shear stress. Here, we analyze the steady-state structure of a suspension of monodisperse silica microspheres in the shear-thickening regime. Using dynamic measurement of boundary stress, we show that the flow is characterized by a cluster of high-stress fronts that propagate in the flow direction at a speed of 1/2 relative to the top plate of the rheometer. We apply high-speed line scan imaging to reveal dramatic fluctuations in particle speed, ordering, and concentration associated with the fronts and show that the structure is consistent with transiently jammed networks that contain high interparticle stresses that percolate across the rheometer gap, but which are present only briefly during the passage of the high-stress fronts.