Adding polymers to a fluid is known to affect both laminar and turbulent flows. Polymers are known to reduce drag in turbulent flows whereas at low Reynolds, viscous dominated, flows (Re<< 1) they induce elastic instabilities leading to a chaotic, inertialess flow state known as elastic turbulence. These affects have their roots in fundamental polymer-flow interactions and in particular the stresses generated by the stretching of the polymers in flow. Although such elastic stresses have been shown to destabilise flows in the absence of inertia, the interaction of fluid viscoelasticity with inertia in laminar flows, associated elastic instabilities and the transition to ‘elasto-inertia turbulence’ are poorly understood.
Using a Taylor Couette flow configuration- a paradigm for hydrodynamic instability- and flow visualisation methods we have elucidated the flow transitions (see figure below) of a Boger (Newtonian but elastic) fluid from Couette flow to disordered flow oscillations and elasto-inertia turbulence (EIT). We have shown that the transition to elasto-inertia turbulence is elasticity driven, attributed to elastic waves that interfere with the inertia, vortical structures present in the flow.
However, the nature of EIT and the exact mechanisms involved in the laminar –EIT transition are poorly understood. In particular; there is a paucity of experimental data and many unresolved questions. In this project we will apply advanced flow diagnostic techniques in macroscale and microscale flows of polymer solutions of varying viscoelasticity with a view to elucidate the nature of EIT, establish onset criteria and harness it to enhance transport phenomena.
We are looking for an enthusiastic and highly motivated engineering or physics/applied maths graduate with excellent knowledge of fluid mechanics and an interest in complex fluids to join our group (FluME). Strong analytical, organisation and communication skills, creativity and an aptitude for experimental work are essential. Matlab programming skills are highly desirable.
This funding is available to UK and EU (non-UK) nationals subject to EPSRC student eligibility requirements. We actively encourage the application of female applicants for this position.
Eligible applicants should contact Prof Stavroula Balabani (email@example.com) forwarding a CV (including at least two referees), a covering letter and a transcript of results (listing all subjects taken and their corresponding grades/marks) by 15th July 2020. We expect the successful candidate to start in October 2020.