The effect of an isolated cylindrical roughness element on a semi-infinite flat plate in rarefied Mach 6 flow is studied using Direct Simulation Monte Carlo methodsThe effect of an isolated cylindrical roughness element on a semi-infinite flat plate in rarefied Mach 6 flow is studied using Direct Simulation Monte Carlo methods Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2024-12-202022enView Video Presentation: https://doi.org/10.2514/6.2022-4029.vid The effect of an isolated cylindrical roughness element embedded in a laminar boundary layer on a semi-infinite flat plate in rarefied Mach~6 flow is studied using the Direct Simulation Monte Carlo method. Steady state solutions are computed only in the three-dimensional configuration, two-dimensional results are obtained on the symmetry plane cutting through the cylinder center and the topologically different structure of laminar separation ahead of and behind the roughness element is documented and briefly discussed. Linear BiGlobal instability analysis of the flow field downstream of the roughness element has revealed stable, traveling, symmetric global modes.http://creativecommons.org/licenses/by/4.0/AIAA AVIATION 2022 ForumProceedings of the AIAA AVIATION 2022 Forum Klothakis Angelos Κλωθακης Αγγελος Dylewicz Kamil Theofilis, Vassilis Sawant Saurabh S. Levin Deborah A. American Institute of Aeronautics and Astronautics Direct Simulation Monte Carlo method Laminar Turbulent Transition Two dimensional flow Navier Stokes equations Kinetic theory