Local dynamic perturbation effects on amplitude modulation in turbulent boundary layer flow based on triple decomposition

This work studies amplitude modulation (AM) of a turbulent boundary layer flow perturbed by a wall-mounted piezoelectric (PZT) actuator. Hot-wire measurements were executed downstream of the PZT actuator working at a certain frequency but several different amplitudes. Turbulent nonlinear fluctuations acquired by triple decomposition were devoted to observing the AM effects. The PZT actuator has a significant impact on the distribution of AM coefficients and joint probability-density functions of large-scale fluctuations and the representatives of small scales in the inner region. Moreover, the energy dependence of small scales on large-scale structures was observed. It proposes that an interlayer region of y(+) less than or similar to 14 characterized by strong energy dependence of high linear slope occurs between innate near-wall structures in the underlying boundary layer flow and wall surface. It was suggested that this interlayer probably suppresses turbulence generation and self-sustaining process of the near-wall cycle. In addition, the conditional AM coefficients further manifests that the AM in the interlayer is insensitive to the condition of large-scale structures. Published under license by AIP Publishing.