An jet of fully expanded Mach number 𝑀 𝑗 = 1.15 and Reynolds number 𝑅𝑒 = 1.25 × 10 6 issues from a contoured converged axisymmetric sonic nozzle operated under-expanded. Large eddy simulations by OpenFOAM software model the unsteady jet. The shock cell train in the jet plume is captured by a modified Roe approximate Riemann solver. Shock-associated noise and mixing noise radiate to the acoustic far-field. The far-field noise directivity and spectral content are predicted by the Ffowcs Williams and Hawkings acoustic analogy implemented in libAcoustics in OpenFOAM. The aerodynamic and acoustic predictions compare favourably with published numerical predictions and experiments. This provides confidence in the use of OpenFOAM combined with libAcoustics for studying the flow and noise from high speed jets towards identifying more effective, economical, and sustainable methods of high speed jet noise abatement and control at source.

Transonic flow past a sphere is investigated by Large Eddy Simulations. The Reynolds number based on the diameter of the sphere and on the free-stream quantities is 1000, while the free-stream Mach number is 0.9. This regime generates a weakly supersonic flow behind the sphere, with a stationary compression wave a few diameters downstream which traverses the developing turbulent wake. The focus of this study is the sound radiated from the wake turbulent structures and their interaction with the stationary compression wave. This direct aeroacoustic computation shows a spiral pressure wave radiating from the base flow precessing about the free-stream unit vector passing through the centre of the sphere. The main acoustically active region is the stationary compression wave-wake interaction one. The localised supersonic flow over the sphere prevents the upstream radiation in a cone of silence type effect within a narrow solid angle upstream of the sphere, which could be exploited for passive noise control.