Environmental noise is a global concern that has far-reaching impacts on human health. Of particular interest is the aerodynamic noise generated by solid surfaces, which is widely encountered in various engineering applications. Extensive research efforts have been dedicated to understanding and mitigating this type of noise. This study presents a computational investigation of the aerodynamic noise generated by a circular cylinder or an airfoil in a cross-flow, particularly at low Reynolds numbers. These cases represent conical problems of unsteady aerodynamics and acoustics. By examining the flow and noise generation around these simplified geometries, important insights into the underlying aeroacoustic physics are obtained, which can be further applied to more complex flow scenarios...[ Read more ]

Environmental noise is a global concern that has far-reaching impacts on human health. Of particular interest is the aerodynamic noise generated by solid surfaces, which is widely encountered in various engineering applications. Extensive research efforts have been dedicated to understanding and mitigating this type of noise. This study presents a computational investigation of the aerodynamic noise generated by a circular cylinder or an airfoil in a cross-flow, particularly at low Reynolds numbers. These cases represent conical problems of unsteady aerodynamics and acoustics. By examining the flow and noise generation around these simplified geometries, important insights into the underlying aeroacoustic physics are obtained, which can be further applied to more complex flow scenarios involving realistic geometries.

The present study employs a Direct Noise Computation approach, utilizing compressible Large Eddy Simulation to simultaneously simulate the flow and noise phenomena. The simulations accurately capture both the aerodynamic and acoustic components of the flow and are validated against reference experimental and simulation data. In the flow over a circular cylinder, the shedding of vortical cores in the wake is recognized as the primary mechanism responsible for generating tonal noise. However, when studying the flow over an airfoil, additional aeroacoustic phenomena have been observed. These include the presence of a convective boundary layer instability on the airfoil surface, which interacts with the wake vortex shedding and the resulting noise emission. This interaction gives rise to an intricate phenomenon known as the Aeroacoustic Feedback Loop, leading to the generation of multiple, co-existing tones that are separated by an equal frequency value.