DNS of a Tollmien-Schlichting Wave Interacting with a Roughness Modeled via Body-fitted and Approximation Methods

View Video Presentation: https://doi.org/10.2514/6.2021-2500.vid Laminar to turbulent transition is often initiated by small and random disturbances which penetrate the boundary layer through a receptivity mechanism. This process generates the named Tollmien-Schlichting (T-S) waves that evolve downstream and eventually lead to turbulence through non-linear effects. Real surfaces are not perfectly smooth and even tiny imperfections can affect the transition process. Investigate the effects of such a small element is a challenge for several codes due the high refinement level required. For this reason, approximated methods for roughness effects inclusion are usually used. Here, we investigate the interaction between a T-S wave and a roughness element with height equals to 5% of local displacement thickness. A body-fitted and an approximated roughness methods are compared. Preliminary results show good agreement for baseflow far from the roughness but some limitations are observed for approximated method when the T-S disturbance is included.