Séminaire de Sandra Lerouge

Purely elastic instability and turbulence in viscoelastic solutions
 

Sandra Lerouge, Laboratoire Matière Systèmes Complexes, Université de Paris Cité

Purely elastic turbulence has been observed in polymer solutions flowing in curvilinear flows by Steinberg's group in 2000. It is usually considered as a spatially smooth and temporally random flow, characterized by a strong increase of the flow resistance with subcritical character and a steep power-law decay of the velocity fluctuations power spectrum. Over the past decade, strongly disordered flows, reminiscent of purely elastic turbulence, have been observed in another type of viscoelastic fluid, which share a formal analogy with polymers: the solutions of giant micelles.
This talk will be divided into two parts. In the first one, I will present the phenomenology of the flow of giant micelles in a Taylor-Couette device and I will discuss the role of the curvature ratio of the flow cell on the onset of the turbulent threshold. The second part will be devoted to the von Karman swirling flow of the benchmark polymer solution used by Steinberg's group. I will focus on the base flow before discussing the transitional pathway to elastic turbulence.