## Abstract

Since wall-pressure fluctuations would form a practically-robust input to a real-time active controller of wall-bounded turbulence, it is of high practical interest to study the scaling behavior of the wall-pressure-velocity coupling. This work investigates the coupling of the wall-pressure fluctuations with the streamwise and wall-normal velocity fluctuations. Both the gain (or coherence) and phase spectra of the wall-pressure-velocity transfer kernel are assessed using a comprehensive database, available from direct numerical simulations of turbulent channel flow. With data spanning a decade in friction Reynolds number Re_{τ} ∼ 550-5200, a 1D analysis (in terms of the streamwise wavelength, λ_{x}) reveals that the streamwise velocity and wall-pressure are most strongly coupled at a self-similar wall-scaling of λ_{x}/y ≈ 14. For the wall-normal velocity component, the strongest coupling appears at approximately half this ratio (λ_{x}/y ≈ 8.5). An analysis of the kernel's phase demonstrates that both the coherent fluctuations of streamwise and wall-normal velocity obey a forward-leaning inclination angle of α ≈ 30^{◦}. When extending the analysis to 2D (as a function of λ_{x} and λ_{z}), the peak-coherence for p_{w} and u still resides close to λ_{x}/y ≈ 14 and is reasonably symmetric around λ_{x}/λ_{z} = 2.3. The 2D coherence for pw and v peaks around λ_{x}/λ_{z} = 1.0. Both the 2D coherence for pw and u, and p_{w} and v, adhere to a wall-scaling with y. Scaling behaviours identified in this work will aid the efficacy of real-time controllers, by for instance the implementation of data-derived FIR filters to only control velocity structures that are captured through wall-pressure measurements.

Original language | English |
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Number of pages | 6 |

Publication status | Published - 2022 |

Event | 12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022 - Osaka, Virtual, Japan Duration: 19 Jul 2022 → 22 Jul 2022 |

### Conference

Conference | 12th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2022 |
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Country/Territory | Japan |

City | Osaka, Virtual |

Period | 19/07/22 → 22/07/22 |

### Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-careOtherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.