A proper orthogonal decomposition analysis upon aerodynamic structures under clean and rough conditions

A transitional flow regime is known to induce complex structures upon aerodynamic geometries such as airfoils, and the dynamics of laminar separation bubbles (LSBs) pose a relevant research field. In addition being affected by Reynolds value itself, LSBs are shown be equally sensitive surface roughness airfoils. The study analyses wind tunnel-derived surface-pressure distribution datasets obtained for particular airfoil standard family developed National Advisory Committee Aeronautics (NACA), namely, NACA0021, subjected range 0.8×104<Re<1.6×104 at different angles attack under two configurations that correspond clean roughened surface. analysis undertaken via proper orthogonal decomposition (POD) technique. results show temporal series data processing most energetic POD modes recovers position LSBs, properly capturing closure point and, hence, turbulence transition location. Some observed closely related, in terms shape, present reattachment on 5:1 rectangular cylinder. This could indicate there recognizable pattern coherent pressure fluctuations when it comes reattached flow. Therefore, principal component presented this can used determine or presence LSB.