Manuel Ferreira

University of Southampton · Faculty of Engineering and the Environment

Mean-flow measurements of turbulent boundary layers over porous walls (permeable and rough) with varying pore size (s), permeability (K) and thickness (h) are presented across a wide range of friction Reynolds numbers (Reτ≈2000–18000) and permeability based Reynolds numbers (ReK≈1.5–60). The mean wall shear stress was determined using a floating el...

We present a cross-correlation based analysis of the acoustic field generated in the wake of NACA 0012 and NACA 65410 aerofoils at a chord-based Reynolds number Rec = 75000 as obtained from pressure fields reconstructed from a series of planar time-resolved Particle Image Velocimetry (PIV) experiments. The experiments are performed in a water chann...

In this experimental study, multiscale rough surfaces with regular (cuboid) elements are used to examine the effects of roughness-scale hierarchy on turbulent boundary layers. Three iterations have been used with a first iteration of large-scale cuboids onto which subsequent smaller cuboids are uniformly added, with their size decreasing with a pow...

We experimentally investigate the surface drag characteristics of a staggered-distributed cube array and its interaction with the turbulent structure of the overlying flow. Instantaneous maps of the pressure field, inferred from in-plane velocity data are used to estimate the forces acting on a target roughness element. Coupled statistics of the fo...

In the published article Ferreira and Ganapathisubramani (2020), Eq. (4) should read instead

Real wind turbines experience a wide range of turbulent shear flows that naturally occur within the atmospheric boundary layer, however, these are often difficult to simulate in experiments. An active grid was used to expand the testable parameter space compared to conventional methods. Specific focus was placed on decoupling the shear from the tur...

In-plane velocity measurements from PIV are used to estimate the pressure field above and within the canopy of two staggered arrays of cuboids, with distinct height distributions, via 2D-RANS and 2D-TH. The viability of this approach is examined by first comparing the mean drag profiles against reported wind-tunnel measurements that were carried ou...

The sheer scale and nature of urban boundary layers present a number of practical challenges that make remarkably difficult to experimentally determine the aerodynamic characteristics of the surface roughness, or to obtain a complete description of the flow field within the canopy layer, including static-pressure measurements. Consequently, there i...

Turbulent flow over the porous surface is one of the least documented problems, despite having the potential to affect a wide range of applications. This study presents an experimental investigation of turbulent boundary layer over open cell porous foam where the pore size and foam thickness are systematically varied. Hot-wire anemometry, Planar an...

Indirect methods to estimate surface shear stress are commonly used to characterise rough-wall boundary-layer flows. The uncertainty is typically large and often insufficient to carry out quantitative analysis, especially for surface roughness where established scaling and similarity laws may not hold. It is, thus, preferable to rely instead on ind...

Peak locking in stereoscopic particle image velocimetry (S-PIV) is often overlooked, albeit the existence of studies demonstrating an influence on turbulent statistics. Peak locking occurs when the seeding particles have an image diameter in the range of 1-2 pixels. Defocusing the camera lens slightly can conveniently address the problem. However,...