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Abstract:
Rotation effects on turbulence features have been examined in viscoelastic spanwise-rotating plane Couette flows (RPCF) at the Reynolds number Re = 1300 and the Weissenberg number Wi = 5, by using of direct numerical simulations for the rotation number R o = 0.02 - 0.9. Here, Re represents the ratio of inertial forces to viscous forces, and Wi and Ro quantify the strength of fluid elasticity and system rotation, respectively. Based on the detailed examinations of the turbulent kinetic energy and Reynolds stress budgets as well as vortical structures, the viscoelastic RPCF can be classified roughly into three regimes: weak rotation for R o ≤ 0.1, intermediate rotation for 0.1 < R o < 0.4, and strong rotation for R o ≥ 0.4. Essentially, the comprehensive rotation effects are inherent to the rotation-driven vortical change characterized by an enhancement as Ro is changed from weak to intermediate rotation and a followed suppression at the elasto-inertial turbulence (EIT) state of strong rotation. Specifically, the turbulent kinetic energy and Reynolds stress at Ro = 0.9 are found less than 10% of those at Ro = 0.2. Of particular interest, at weak and intermediate rotation, intense polymer-turbulence interaction is found to occur primarily in the extensional flows between two neighboring roll cells, whereas for the high-Ro EIT state, it happens in the bulk region as the small-scale turbulent vortices serve to homogenize the polymer dynamics via their vortical circulations. The present finding has shed some new light onto the polymer-turbulence interaction under system rotation.
