ICMCS seminar - Purely elastic turbulence: recent advances in channel flows

Title: Purely elastic turbulence: recent advances in channel flows

Abstract: Flows of complex fluids (such as polymers, colloids, emulsions, pastes, etc.) are abundant in everyday life. One can think of pouring shampoo or squeezing toothpaste from a tube, but also of fibre-spinning and plastic extrusion. Such flows often exhibit unexpected complexity, with an archetypal example being elastic turbulence—chaotic motion exhibited by dilute polymer solutions. While its appearance is understood theoretically in flows with curved streamlines, there are still many open points about elastic turbulence in straight pipes and channels. In this seminar, we summarise the key aspects of the Newtonian turbulence problem. This is followed by a general overview of non-Newtonian fluids and, in particular, of viscoelasticity. To illustrate the most recent progress in this field, we report simulations of elastic turbulence in a parallel flow geometry where we focus on the zero Reynolds number case in the well-diluted polymer regime. A systematic investigation of the dependence on the Weissenberg number shows that turbulence production is concentrated along the centre plane of the channel away from the walls. This is an opposite behaviour from the Newtonian counterpart in which turbulent motion is predominantly located near the bounding walls. The analysis of the Wi dependence of velocity statistics and gradient dynamics reveals a degree of intermittency even in the present inertialess configurations.

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https://ed-ac-uk.zoom.us/j/81211470751

Meeting ID: 812 1147 0751
Passcode: ICMCS123