Axial Flow Effect on the Stability of Circular Couette Flow

We investigate the effect of an axial Poiseuille annular flow on the stability of Taylor vortices via numerical simulation using CFD Ansys Fluent software. The working conditions are identical to those of the Taylor- Couette experimental device of the LaSIE laboratory, where the inner cylinder is rotated. An incompressible fluid of density ρ= 998 kg/m3, with a kinematic viscosity 𝜈 = 1.004 ∗ 10m2/s at a temperature T= 19.5 °C is considered. The geometrical parameters of the flow system are characterized by a height H=275 mm, a radius ratio η=0.804, and an axial aspect factor Γ=45.45. The axial Reynolds number and Taylor number are respectively in the ranges of 0 ≤ R􀯘􀳌􀳣 ≤ 12 , and 0 ≤ 𝑇𝑎 ≤ 142.25. Flow control is carried out according to two distinct protocols to bring out the effect of axial flow on the evolution of the Taylor vortex Flow (TVF). The first consists of superimposing an azimuthal flow around the critical TVF threshold with increasing axial flow until the Taylor vortices disappear. In the second, an axial field is set and the Taylor number is varied until onset of the TVF mode. It is predicted that in the presence of an axial flow, the critical threshold for first instability triggering (TVF) is delayed. In addition, the ratio of the axial phase velocity to the mean axial velocity of the axial base flow is 1.16. This value agrees well with previous results reported in literature.