Numerical investigation of non-Newtonian fluids in annular ducts with finite aspect ratio using lattice Boltzmann method.

摘要: In this work the instability of Taylor-Couette flow for Newtonian and non-Newtonian fluids (dilatant pseudoplastic fluids) is investigated cases finite aspect ratios. The study conducted numerically using lattice Boltzmann method (LBM). many industrial applications, apparatuses installations drift away from idealized case an annulus infinite length, thus end caps effect can no longer be ignored. inner cylinder rotating while outer one walls are maintained at rest. two-dimensional nine-velocity (D2Q9) model developed Bhatnagar-Gross-Krook approximation used to obtain field obeying power-law model. combined effects Reynolds number, radius ratio, index n on characteristics analyzed annular space ratio. Two modes obtained: a primary Couette (CF) mode secondary Taylor vortex (TVF) mode. structures so obtained different another. critical number Re(c) passage exhibits lowest value highest dilatant fluids. findings useful studies swirling non-Newtonians in axisymmetric geometries LBM. changes CF TVF its structure switches two-cells four-cells regime both Contrariwise fluids, 2-4-2 passing four cells again configuration. Furthermore, presents monotonic increase with fluid, as ratio grows, transition regimes tend appear higher numbers.