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 1^st critical Reynolds number, axisymmetric stationary Taylor-Vortex (ASTV) is observed. As the Reynolds number is increased to its 2^nd 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 3^rd critical Reynolds number. As the Reynolds number is increased further, APSAF turns into a non-axisymmetric periodic secondary axial flow (NAPSAF) at the 4^th critical Reynolds number. NAPSAF transforms into a non-axisymmetric complex periodic flow (NACPF) at a critical value denoted as the5^th critical Reynolds number. Finally, at the 6^th critical Reynolds number, non-axisymmetric non- periodic random flow (NANPRF) appears.