Swelling soft hydrogel particles in turbulent Taylor-Couette flow: From particles in turbulence to jamming

Using swelling soft hydrogel particles we study turbulent particle-laden flows with varying volume fraction from below 1% to 75%. We monitor the torque on the inner cylinder, temperature in the flow, particle size, and particle velocity throughout the entire swelling process of the particles. During the initial stages (small φ) the torque on the inner cylinder increases, connected to an increase in effective viscosity. At high volume fractions φ ≥ 0.55 the particles attenuate the Taylor vortices, decreasing the torque. At volume fractions φ ≥ 0.65 the flow changes to a pressure imposed flow, due to the increasing internal particle pressure, further increasing the torque. We obtain the particle velocity profiles and observe a shear band with a thickness of 1 particle close to the inner cylinder. At φ ≈ 0.75 the particles are unable to move with respect to each other and undergo as one block solid body rotation, where the only slip is at the smooth inner and outer cylinders. This work sheds new light on turbulent flows of dense suspensions near jamming and presents a new method to achieve high volume fractions in turbulent flows.