Recent advances in the understanding of the structure of boundary-layer turbulence form the basis of a new conceptual model tot the fluctuating velocity field. In this, an “active” mode of small-scale motion is coupled to a large-scale “passive” mode by aid of wave-mechanical considerations. The small-scale motion originates during the intermittent “bursting” in the wall layer leading to excitation of large-scale, lightly damped, traveling shear waves. It is argued that the passive wave-like mode gives the major contribution to the pseudosound, whereas the active bursting mode serves as the predominant source for the radiative noise. It is shown that the bursting mode gives rise to compact noise sources of both dipole and quadrupole type whose strengths are related to the turbulent shear stress production.
No takes yet. Share an insight, caveat, or question.
Mårten T. Landahl (1973) studied this question.