Nonlinear optimal perturbations in pipe flow of shear thinning fluids

Transition to turbulence in a circular pipe remains an active open problem in fluid dynamics. A large body of work in wall-bounded shear flow has been dedicated to find Exact Coherent Structures (ECS) and optimal perturbations that trigger turbulence. Extending the investigation to non-Newtonian fluids is of particular interest for industrial processes. The effects non-Newtonian viscosity have been studied by R. Liu and Q. S. Liu, Phys. Rev. E, 85 (2012). However, recent experimental results (C. Wen, et al, Phys. Rev. Fluids 2, 2017) raise new questions regarding the stability of these fluids. Here we present some numerical results to expand the relatively unexplored study of shear thinning flows.