Hibernating states in elastoinertial turbulence

We report on the spatiotemporal evolution of the flow structures observed in a jet of dilute polymer solution entering a quiescent bath of either a Newtonian or a viscoelastic fluid. We study elastoinertial turbulence (EIT) in both Lagrangian and Eulerian form using high-speed digital Schlieren imaging and laser doppler velocimetry (LDV). Despite the spectral universality of the velocity and concentration fluctuations observed at fixed locations along the centerline of the turbulent jet in the EIT state, the Lagrangian structure can be tuned by varying the viscoelasticity of the surrounding bath or the extensibility of the polymer chains. The fluctuations far from the nozzle switch between active and hibernating states for jets in the viscoelastic bath. The percentage of time that the flow spends in the active and hibernating states, respectively, is set by the Reynolds number and the elasticity mismatch between the jet and the bath.