Boundary Layer Stability with Embedded Rotating Cylindrical Roughness Element

Abstract

Linear stability theory (LST) and direct numerical simulations (DNS) are used to investigate the instability of boundary layer flow with an embedded rotating cylindrical roughness element. The non-linear formulation of the perturbation evolution is implemented and solved with the second-order finite volume solver OpenFOAM, which is validated by comparison with LST prediction with respect to Tollmien-Schlichting waves. Dynamic mode decomposition (DMD) is then used to obtain the frequency separated disturbance modes. To obtain an insight into the instability mechanism, perturbation kinetic energy analysis is followed. Results reveal the possible stabilization effect of such a flow setup.