Curvature Effects on Wall Pressure Fluctuations in Moderate-Reynolds-Number Channel Flow

Abstract

Abstract

Direct numerical simulations of turbulent flow in longitudinally curved channels are used to investigate wall-pressure fluctuations over convex surfaces across a wide range of Reynolds numbers and curvature ratios. Inner scaling based on the friction velocity is shown to fail in collapsing the intensity of wall-pressure fluctuations when curvature is present. In contrast, an outer scaling based on the peak mean velocity yields a robust collapse for sufficiently large Reynolds numbers, leading to a simple universal expression for the pressure fluctuation intensity. Spectral analysis reveals that wall curvature significantly modifies the low-frequency content of the wall-pressure spectrum. The high-frequency tail is well described by the exponential-decay model for both plane and curved channel flows, rather than the more commonly assumed power-law distribution. Based on these findings, a new parametric model incorporating outer velocity scaling and an exponential high-frequency decay is proposed and shown to outperform existing empirical formulations across Reynolds numbers and curvature ratios.