Stochastic estimation and flow sources associated with surface pressure events in a turbulent boundary layer

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Abstract
The ability of stochastic estimation to capture the conditional streamwise velocity field associated with wall-pressure events was investigated using simultaneous hot-wire and microphone measurements over the Reynolds number range: 1437⩽Reθ⩽5670. The velocity measurements were conducted at the same streamwise and spanwise location as the wall-mounted microphone but at various heights in the boundary layer, spanning the buffer and logarithmic regions. The results show that utilization of the wall-pressure as the event for the stochastic estimation requires the inclusion of both the linear and quadratic terms in order to provide an accurate representation of the conditional velocity field. The need for the inclusion of the quadratic term, which is unlike published results based on velocity and Reynolds stress events in wall-bounded flows, is attributed to the influences of the turbulent–turbulent pressure source term. Additionally, examination of the energy content of the quadratic component of the stochastic estimation and its Reynolds number scaling suggests that the quadratic term is associated with motions that scale with the boundary layer thickness.