Physical characteristics of wall pressure fluctuations for fully developed turbulent annular channel flows

This study investigates the physical characteristics of wall pressure fluctuations for fully developed turbulent channel flows using the large eddy simulation. Turbulent annular channel flows with three radius ratios ( R-in/R-out = 0.33, 0.43, and 0.50) are numerically studied. Here, R-in and R-out are the radii of inner and outer cylinders, respectively. A planar channel is set up to serve as a validation case, also representing a specific condition R-in/R-out -> 1. The computational method is carefully validated against previous direct numerical simulation data. On this basis, the physical characteristics of wall pressure fluctuations on the inner and outer walls are compared. The trend of the wall pressure fluctuations spectra is consistent, while the outer cylinder wall exhibits higher spectral magnitudes. Then, the effects of the radius ratio on wall pressure fluctuations are studied. As the radius ratio decreases, the spectral magnitude on the inner cylinder wall shows a slight reduction at low wavenumbers and frequencies, whereas on the outer cylinder wall, it increases significantly across the entire range of wavenumbers and frequencies. This suggests that the convex curvature on the inner wall has a mild effect on structures with large streamwise and spanwise length scales, while the concave curvature on the outer cylinder sides significantly impacts flow structures across all scales.