Numerical Investigation of Non-Newtonians Fluids Flows between Two Rotating Cylinders Using Lattice Boltzmann Method

Abstract

A numerical investigation is performed for non Newtonian fluids flow between two concentric cylinders. The D2Q9 lattice Boltzmann model developed from the Bhatangar!Gross!Krook (LBGK) approximation is used to obtain the flow field for fluids obeying to the power!law model. The inner and outer cylinders rotate in the same and the opposite direction while the end walls are maintained at rest. The combined effects of the Reynolds number (Re) of the inner and outer cylinders, the radius ratio (η) as well as the power!law index (n) on the flow characteristics are analyzed for an annular space of a finite aspect ratio (Γ). Two flow modes are obtained: a primary mode (laminar stable regime) and a secondary mode (laminar unstable regime). The so obtained flow structures are different from one mode to another. The transition critical Reynolds number Re c from the primary to the secondary mode is analyzed for the co!courant and counter!courant flows. This crit ical value increases as n increases. The prediction of the swirling flow of non Newtonians fluids in axisymmetric geometries is shown in the present work.