Publié le 27 novembre 2025
–
Mis à jour le 27 novembre 2025
Date(s)
le 2 décembre 2025
Café : 15h
Séminaire: 15h15
Séminaire: 15h15
Lieu(x)
Salle des séminaires
Revisiting purely elastic turbulence in von Karman swirling flow of viscoelastic fluids
Seminars of the Institut de Physique de Nice,
Abstract:
Complex fluids often exhibit viscoelastic properties, i.e. a mix of solid- and liquid-like behavior. Unlike simple liquids, these materials are structured on a mesoscopic scale. During processing or use, they undergo moderate or strong flows, which can easily affect their mesostructure. In turn, these structural modifications can trigger instabilities in the flow itself. These instabilities occur at flow rates at which inertial effects are usually negligible, i.e. when the Reynolds number, which compares inertial and viscous effects, is low. Driven by elastic forces, they give rise to disordered flows and complex spatiotemporal behaviour, which is sometimes reminiscent of inertial turbulence.
Purely elastic turbulence in polymer solutions was first characterised in von Kármán swirling flow. The main features of this disordered flow state are a significant increase in flow resistance with strong hysteretic characteristics, and excitation across a broad range of spatial and temporal scales, resulting in steep power-law decay in the power spectra of velocity fluctuations. Furthermore, the transition to elastic turbulence in this flow geometry is supposed to be mediated by the existence of a large toroidal vortex at the scale of the whole setup.
In this study, we revisit the transition to purely elastic turbulence in polymer solutions in von Karman swirling flow. Our focus is on the effect of the flow history on the system's mechanical response, alongside a detailed characterisation of the flow structure. I will show some findings that challenge some of the results established so far.
Abstract:
Complex fluids often exhibit viscoelastic properties, i.e. a mix of solid- and liquid-like behavior. Unlike simple liquids, these materials are structured on a mesoscopic scale. During processing or use, they undergo moderate or strong flows, which can easily affect their mesostructure. In turn, these structural modifications can trigger instabilities in the flow itself. These instabilities occur at flow rates at which inertial effects are usually negligible, i.e. when the Reynolds number, which compares inertial and viscous effects, is low. Driven by elastic forces, they give rise to disordered flows and complex spatiotemporal behaviour, which is sometimes reminiscent of inertial turbulence.
Purely elastic turbulence in polymer solutions was first characterised in von Kármán swirling flow. The main features of this disordered flow state are a significant increase in flow resistance with strong hysteretic characteristics, and excitation across a broad range of spatial and temporal scales, resulting in steep power-law decay in the power spectra of velocity fluctuations. Furthermore, the transition to elastic turbulence in this flow geometry is supposed to be mediated by the existence of a large toroidal vortex at the scale of the whole setup.
In this study, we revisit the transition to purely elastic turbulence in polymer solutions in von Karman swirling flow. Our focus is on the effect of the flow history on the system's mechanical response, alongside a detailed characterisation of the flow structure. I will show some findings that challenge some of the results established so far.