Elastic and elasto-inertial turbulence in channel flows

Turbulence production in wall-bounded parallel shear flows of Newtonian fluids is mostly located close to the bounding walls. In contrast, our recent work demonstrates [1] that in purely elastic turbulence the production is concentrated along the centre plane of the channel away from the walls. This begs the question as to what type of production occurs in turbulent flows of Non-Newtonian fluids at finite Reynolds number, that is, in elasto-inertial turbulence. Observations suggesting wall-mode production have been made from numerical simulations, however, recent experimental results suggest a co-existence of wall- and centre-mode activity.

Here, we report results from a systematic study of the Weissenberg-Reynolds parameter space by direct numerical simulation, showing that centre-line production extends significantly into the larger-Reynolds-number region, thus connecting purely elastic and elasto-inertial turbulence. This suggests that the origin of elasto-inertial turbulence is purely elastic.

[1] Martin Lellep, Moritz Linkmann, and Alexander Morozov, Purely elastic turbulence in pressure-driven channel flows, Proc. Natl. Acad. Sci. USA 121, e2318851121 (2024)