The study of Taylor-Couette flow structure under the influence of macroscale corrugated surface

Taylor-Couette flow with a stationary corrugated (a longitudinal groove, amplitude to wavelength ratio 0.25 and amplitude to average gap ratio 0.5) outer cylinder and a rotating smooth inner cylinder has been studied using Direct Numerical Simulation (DNS) for the radius ratio 0.5 and Reynolds number range of 60 to 650. There are six distinct flow regimes observed in this study where, at the 1st critical Reynolds number, axisymmetric stationary Taylor-Vortex (ASTV) is observed. As the Reynolds number is increased to its 2nd critical value, a pair of axisymmetric stationary secondary vortices (ASSTV) are observed in the minimum gap region of the inner cylinder. Following that, axisymmetric periodic secondary axial flow (APSAF) appears at the 3rd critical Reynolds number. As the Reynolds number is increased further, APSAF turns into a non-axisymmetric periodic secondary axial flow (NAPSAF) at the 4th critical Reynolds number. NAPSAF transforms into a non-axisymmetric complex periodic flow (NACPF) at a critical value denoted as the5th critical Reynolds number. Finally, at the 6th critical Reynolds number, non-axisymmetric non- periodic random flow (NANPRF) appears.