A DNS database of wall-pressure fluctuations beneath turbulent boundary layers with pressure gradients*

Spatiotemporal characteristics of wall-pressure fluctuations induced by turbulent boundary layers with varying pressure gradients are examined using incompressible direct numerical simulations. A series of pressure gradient distributions are generated by applying suction and blowing of different magnitudes at the upper computational boundary, resulting in three separated and three attached flat-plate boundary layers. The root-mean-square values of wall-pressure fluctuations for the separated boundary layers exhibit two peaks: one before the separation in the adverse pressure gradient (APG) region and the other after reattachment in the favorable pressure gradient (FPG) region, consistent with findings from previous numerical studies. In contrast, for the attached boundary layers, only a single peak exists in the APG region, while the fluctuation levels in the FPG region are lower than those in a zero-pressure-gradient boundary layer. Additionally, correlation and spectral analyses are conducted to reveal the substantial impact of pressure gradients on the structure of wall-pressure fluctuations. The database is used to develop a machine learning-based surrogate model for efficient prediction.