The laminar–turbulent transition of a supersonic boundary layer induced by an isolated roughness element is investigated using direct numerical simulation, BiGlobal linear stability theory, and the three-dimensional parabolized stability equation. Cylindrical and diamond-shaped roughness elements are investigated in combination with different wall temperatures. Direct numerical simulations show that the cylinder configuration induces an earlier transition than the diamond configuration, with the interaction between the separated shear layer and the counter-rotating vortices causing the transition. BiGlobal analysis and the parabolized stability equation confirm the existence of two unstable instability modes in the wake region, namely, a symmetric mode and an antisymmetric mode, with the former being strongly dominant. The wall cooling and heating effects are studied by changing the wall temperature. Wall heating lifts the inlet boundary layer and weakens the separated shear layer. This, in turn, weakens the wake instability and delays the transition. The antisymmetric model disappears as the wall heating increases. Wall cooling accelerates the transition by enhancing the distortion of the roughness wake, resulting in stronger instabilities. Finally, the Reynolds number based on the momentum defect is used to define the transition criterion, and this is found to be in good agreement with the present simulation results.
Roughness-Induced Transition in Supersonic Boundary Layers with Wall Heating and Cooling Effects
AIAA Journal ; 62 , 7 ; 2458-2475
2024-04-04
18 pages
Article (Journal)
Electronic Resource
English
Roughness-Induced Transition in a Supersonic Boundary Layer
Online Contents | 2016
|Supersonic Boundary Layers with Periodic Surface Roughness
Online Contents | 2008
|Roughness Induced Transition in a Supersonic Boundary Layer
British Library Conference Proceedings | 2013
|