Microscale fluid structure interactions of non Newtonian fluids peeling a linearly elastic sheet

In this study, we investigate the transient fluid structure interactions (FSI) of a non-Newtonian fluid peeling a Hookean sheet at low Reynolds numbers (Re) .The rheology of the fluid is rendered by the simplified Phan-Thien-Tanner (sPTT) model. Invoking the lubrication approximation for fluid flow and considering the relative time scale for deformation and the relaxation time of the polymer, we solve a reduced problem for the evolution of the deformed height in time and space. An order of magnitude analysis of the resultant equation reveals two distinct regimes of peeling, based on the relative magnitude of the viscoelasticity and FSI parameters, further aided by similarity solutions. On inspecting the numerical solution, we infer that the non-Newtonian nature plays a pivotal role in bringing the system to a steady state faster in comparison to a Newtonian fluid. This inference, in turn, further motivates us to investigate the dynamics of peeling actuated by purely shear thinning fluids. Some preliminary results for the peeling actuated by such generalized Newtonian fluids are also presented. To conclude, this study aims to afford to the experimentalist a system of knowledge to a priori delineate the peeling characteristics of a certain class of complex fluids.