Planar sudden symmetric expansion flows and bifurcation phenomena of purely viscous shear-thinning fluids

The goal of a present study is to investigate the effects of the generalized Newtonian fluids on the threshold of the transition from flow symmetry to its asymmetry for the flow through a 1:3 planar sudden expansion. We consider purely viscous shear-thinning fluids covering a range of the index n   of Power law model n=0.6,0.8n=0.6,0.8 and compare them with the Newtonian fluid (n=1.0n=1.0). Sudden expansion fluid flow is studied numerically by solving the two-dimensional momentum equations along with the continuity equation and the Power law rheological model. We report a systematic results in a range of generalized Reynolds number 10≤Regen≤15010≤Regen≤150 with a focus on its critical value. The subsequent effects are investigated by means of a different flow parameters, i.e. generalized Reynolds number (RegenRegen), modified Reynolds number (RemodRemod) and the Reynolds number defined in accordance with the inlet wall viscosity (RewallRewall). Results indicate that the shear-thinning viscous behaviour increases the onset of bifurcation phenomena and the critical value of Reynolds number.