Flow and aeroacoustics control of an inclined wall-mounted cylinder using porous coatings

This study investigates the evolution of flow structures and aerodynamic noise generation around inclined wall-mounted cylinders (FWMCs) at a Reynolds number of 50 000 using large eddy simulation (LES) and the Ffowcs Williams–Hawkings acoustic analogy. The influence of inclination angles on flow dynamics and acoustic responses is examined in detail, with a particular focus on the control effects of porous coatings under various inclinations. The analysis covers aerodynamic forces, shear layer evolution, wake reconstruction, and the development of three-dimensional (3D) vortex structures, highlighting how inclination modifies wake behavior and the distribution of unsteady acoustic sources. The results show that inclination angle significantly alters vortex shedding modes and wake deflection characteristics. Forward inclinations enhance surface attachment and induce asymmetric wake dynamics, while backward inclinations promote vortex flattening. These effects lead to nonlinear changes in drag and noise generation. The introduction of porous coatings improves wall permeability and enhances the dissipation of flow disturbances, effectively suppressing shear layer instabilities and weakening large-scale vortex shedding and noise radiation. Under inclination angles of θ=0° and θ=−45°, the peak sound pressure levels (SPLs) are reduced by 26.5% and 25.9%, respectively, indicating improved wake stability and more localized noise sources. Furthermore, in the backward inclination scenario, excellent noise reduction performance is observed, with a maximum peak sound pressure level reduction of 29.7% at θ=45°. These findings demonstrate that changes in inclination induce more complex three-dimensional flow-acoustic coupling around FWMCs, confirming the effectiveness of porous materials in modulating the flow field and suppressing aerodynamic noise under intricate three-dimensional (3D) wake conditions. The outcomes offer valuable theoretical support for the passive flow control design of bluff-body structures in practical engineering applications.