Visco-elastic CFD: turbulence at zero Reynolds number

Adding even a small amount of dissolved polymer into a fluid can have a dramatic impact on the way it flows. If the flow is turbulent (high-Reynolds-number) to begin with, then the polymer can strongly modify the turbulent eddies and reduce the drag force (in flow through pipes) or even make the flow laminar. Known as the Toms effect, this phenomena is exploited to reduce the pumping costs associated with transporting oil in pipelines. Polymers can also destabilize a low-Reynolds-number steady flow and make it unsteady and chaotic. Such instabilities can produce elastic turbulence, which can greatly increase mixing in microchannels and enhance oil-recovery from underground porous reservoirs.

The source of these phenomena lies in the coupling of the polymer molecules to the flow, which results in a viscoelastic rheology. As a first approximation, such polymer solutions canbe described by continuum constitutive models like Oldroyd-B or FENE-P. Despite being the simplest possible equation of their class, these models are challenging to simulate, especially at the high values of elasticity (Weissenberg number) at which interesting experimental observations are available.

This project will involve using (and extending) an in-house CFD code to simulate polymer solutions. We will focus on situations that correspond to intriguing and unexplained experimental observations. Apart from the in-house code, there will be an opportunityt o explore the use of open-source alternatives as well. The student will gain experience in code development, in addition to expertise in Non-Newtonian fluid dynamics, and turbulence. 

For more information: https://www.che.iitb.ac.in/group/picardo-group/article/turbulent-transport

Collaborators:

Dario Vincenzi, Univ. Cote D'Azur, Nice, France (https://math.unice.fr/~vincenzi/).

Prabhakar Ranganathan, Monash University, Australia (https://www.monash.edu/engineering/prabhakarranganathan)