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Accueil du site > Évènements > Séminaires > Séminaires IRPHE > Archives IRPHE > 2022

Lundi 5 Décembre 2022 / IRPHE

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Séminaire IRPHE

Transport and sedimentation of elastic filaments in turbulent flows

Orateur : Jason R. Picardo / Indian Institute of Technology Bombay

Abstract : The dynamics of long filamentary extensible objects in a turbulent flow has been largely unexplored, despite its relevance to a range of physical situations in nature and industry, including fibres in paper-processing and plastic debris in the ocean. The behavior of such objects becomes particularly intriguing when they extend beyond the small, dissipation scale of the flow ; the mean flow velocity sampled by the object is then dependent on its instantaneous shape, thereby coupling translation to flow-induced deformation. This talk will focus on the transport of filaments in homogeneous isotropic turbulent flow using a simple bead-spring chain model. I will first briefly discuss the preferential sampling behaviour of neutrally buoyant filaments and then focus on heavy sedimenting filaments. The filaments settle faster through the turbulent flow than in a quiescent fluid, but with a strongly fluctuating settling velocity whose variance has a power-law dependence on the filament’s weight but is surprisingly unaffected by its elasticity. In contrast, the tumbling of the filament is closely coupled to its stretching, and will be shown to manifest as a Poisson process with a tumbling time that increases with the elastic relaxation time (and thus the length) of the filament. Open questions, including the subtle role of stiffness, will be discussed.

Date et lieu : le lundi 5 décembre à 11h00, salle de séminaires IRPHE

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