Low-wavenumber wall pressure fluctuations in turbulent flows within concentric annular ducts

Compressible direct numerical simulations of turbulent channel flows in concentric annular ducts of height 2 delta 2 δ 2δ are performed to study the low-wavenumber wall pressure fluctuations (WPF) over cylindrical walls at bulk Mach number upper M Subscript b Baseline equals 0.4 M b = 0.4 Mb = 0.4 and bulk Reynolds number italic Re Subscript b Baseline equals 3000 Re b = 3000 Reb=3000 . The radius of the inner cylinder upper R R R is varied between 0.2 delta 0.2 δ 0.2δ , delta δ δ , 2 delta 2 δ 2δ and normal infinity ∞ ∞ . As upper R <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/cor