Establishing Universal Scaling Laws for Pressure Fluctuations in High Reynolds Number Rough Wall Turbulent Boundary Layers
Technical Report,01 Apr 2015,30 Jun 2018
Virginia Tech, Department of Aerospace and Ocean Engineering Blacksburg United States
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An experimental study of the pressure fluctuations generated by zero-pressure-gradient turbulent boundary layers at high Reynolds numbers over rough walls has been performed. The work, which extends the study of Meyers et al. J Fluid Mech., vol. 268, pp. 261-293, 2015, has been specifically directed at examining the scaling behavior of the pressure fluctuations. Measurements have been made on boundary layers formed over a series of deterministic rough surfaces selected to define, in combination with those of Meyers et al., systematic variations in roughness size, density, shape and distribution as well as surfaces formed from combinations of shape and size. Major findings of this work include the apparent universality of the high frequency viscous scaling proposed by Meyers et al, and that the associated scaling velocity the shear friction velocity is a unique function of roughness Reynolds number and density the fact that low-frequency pressure fluctuations scale most accurately on defect velocities either the convection or boundary layer averaged defect velocity that the mid-frequency behavior of the pressure spectrum cannot in general be scaled since pressure fluctuations in this range are highly dependent on the local topology of the surface. Significant findings also include new insights into the relationship between wall pressure fluctuations and the velocity fluctuations that produce them, as well as direct measurements.
- Fluid Mechanics