Noise amplification in hypersonic blunt body flows

We utilize stochastically-forced compressible linearized Navier-Stokes equations to study the dynamics of hypersonic flows over blunt bodies. Our analysis of the energy of the flow fluctuations around the laminar stagnated flow reveals strong amplification in the presence of background noise. We also provide insights into how changes in different physical parameters, such as the temperature of the blunt body and its curvature, influence the amplification of flow fluctuations. We show that increasing the bluntness and decreasing the wall temperature can significantly enhance the fluctuation amplification. In addition, we also evaluate the global response in the presence of localized sources of stochastic excitations such as those associated with surface roughness. Our approach reveals substantial amplification of flow fluctuations along the convexly curved surface of the blunt leading edges and suggests that amplification of these stochastic excitation sources (e.g., free-stream turbulence and surface roughness) that are unavoidable in experiments might play a crucial role in transition observed over such geometries.