Jamming of growing hydrogel particles in highly turbulent Taylor-Couette flow

To investigate dense suspensions and jamming in turbulent flow, we add superabsorbent hydrogel particles into a turbulent Taylor-Couette flow (Reynolds numbers O(Re) = 10^6). Starting from a small volume fraction of 1.3% the particles slowly grow, altering the volume fraction until a volume fraction of approximately 64% is finally reached (50 times their original volume). We monitor the size of the particles using high speed imaging while simultaneously measuring the torque on the inner cylinder. Comparing this torque to the response of the system for a single-phase fluid we calculate an effective viscosity of the turbulent suspension. The effective viscosity is found to increase when the volume fraction increases. Finally, at high volume fractions, the axial mixing of the system is inhibited, and the system exhibits jamming. Remarkably, the increase of the effective viscosity is non-monotonic in time, which we attribute to shear-banding in the jammed state.