Relationship between wall pressure and velocity-field sources

Abstract

The objective of this investigation is to study the velocity-field sources for the fluctuating wall pressure, determine their locations in the boundary layer, and investigate their physics. The velocity-field sources and partial wall pressures were computed from a database generated by a direct numerical simulation of a low Reynolds number, fully developed, turbulent channel flow. Results show that the mean-shear (MS) and turbulence-turbulence (TT) partial pressures (πMS and πTT, respectively) are the same order of magnitude. The buffer region dominates most of the wave number range; the viscous shear layer is significant at the highest wavenumbers; the buffer and logarithmic regions are important at low wavenumbers. Over most of the wavenumber range, the contribution from the buffer region is the dominant TT component; in the low-wavenumber range, the viscous shear layer, buffer region, and logarithmic region are significant; in the medium and high wavenumbers the viscous shear layer and buffer region dominate. The most important TT partial pressures are π23TT, π13TT and π12TT from the buffer region. It is conjectured that π23TT and π13TT may be generated by quasi-streamwise vortices. π12TT may be due to near-wall shear layers and spanwise vortices. π23TT, π22TT and π33TT from the viscous shear layer are the dominant high-wavenumber partial pressures.