Flow bifurcation transitions of inelastic shear thinning fluids in a channel with sudden contraction and expansion

Abstract

The bifurcation transitions from the symmetric to asymmetric flow regimes in shear thinning fluids in a channel with sudden contraction and expansion were studied by means of numerical simulations. On the example of the Carreau–Yasuda model, the bifurcation diagrams of shear thinning fluids with different viscosity flow curves were revealed along the critical Reynolds numbers of the bifurcation transitions. It was found that increase in variations of viscosity with shear rate leads to a noticeable decrease in critical Reynolds number and increase in dimensions of the angular vortices as compared to Newtonian fluids. The obtained results indicate the enhancement of flow instability of shear thinning fluids in channels with the variable cross-sections.