(577c) Dynamics and Structures of Viscoelastic Turbulence in Transitional Channel Flow

Introducing a trace amount of polymer into liquid turbulent flows can result in substantial reduction of friction drag. This phenomenon has been widely used in fluid transport; however, the mechanism is not fully understood. In this work we perform direct numerical simulations of viscoelastic turbulence in channel flow, using a high-resolution scheme that guarantees the positive-definiteness of polymerconformation tensor without artificial diffusion. It is found that at low to medium Weissenbergnumbers (Wi) the statistics from the high-resolution scheme show no difference from the statistics obtained from spectral code with global artificial diffusion. However the high-resolution scheme is able to resolve a finer spatial structure of the polymer conformation, which exhibits thin sheet structures. Intermittency of low- and high-drag events as well as the anti-correlation between the velocity and polymer stretch are observed in both. Frequency analysis shows that the natural frequency and the burst frequency are similar between Newtonian and low-Wi cases.