Generalized phase average with applications to sensor-based flow estimation of the wall-mounted square cylinder wake

Abstract

We experimentally investigate the three-dimensional wake behind a finite wall-mounted square cylinder at Re = 12 000 and aspect ratio of 4. Focus is placed on the base flow and oscillatory fluctuation. Time-resolved three-dimensional velocity fields are constructed from high-frame-rate particle image velocimetry (PIV) and simultaneously recorded surface pressure measurements. All three velocity components are resolved in a rectangular near-wake region by two orthogonal dense arrays of parallel PIV planes. A key enabler is a generalized phase average incorporating a slowly varying base flow, a variable oscillation amplitude and higher harmonics. These generalizations reduce the instantaneous residual 30 % below those of a traditional phase average. Moreover, the resolved variations reveal analytical constraints of the mean flow and oscillation levels, such as the mean-field paraboloid. The proposed methodology for generalized phase averaging and for construction of three-dimensional velocity fields from two-dimensional PIV data is applicable to a large class of turbulent flows with oscillatory dynamics.

A review of flow-induced noise from finite wall-mounted cylinders

“…The first authors to describe this shedding model for such aspect ratio cylinders were Wang and Zhou (2009), and hence this will be referred to as the 'Wang model'. Bourgeois et al (2011Bourgeois et al ( , 2013 and Hosseini et al (2013) propose a related but inherently different model to that of the Wang model, known as the 'Bourgeois model' . The vortex filaments are shed periodically from either side and are continuously linked at both extremities with connector strands, leading to a fully connected alternating looped structure that is convected downstream.…”

Spectral proper orthogonal decomposition

“…The drawback of this approach is that the investigated flow must feature some symmetries and they must be known a priori. A recent application shows the huge variety of spatial and temporal filtering together with POD to separate different phenomena into different modes (Bourgeois, Noack & Martinuzzi 2013), exemplifying the complexity of this approach.…”

Interscale energy transfer in the merger of wakes of a multiscale array of rectangular cylinders

“…Cantwell and Coles [10], Sonnenberger et al [11]), proper orthogonal decomposition based techniques (e.g. Perrin et al [12]) or even more complex techniques (Bourgeois et al [13]) amongst many others. The particular conditions of the current work, however, limit the choice.…”