Takfarinas Medjnoun

University of Southampton · Aerodynamics and Flight Mechanics Research Group

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...

Wall-bounded flows developing over spanwise heterogeneous surfaces exhibit timeaveraged streamwise vortices when the spanwise characteristic length scale of the surface (S) is comparable to the dominant length scale of flow (δ) (Barros and Christensen, 2014). In this work, we experimentally examine a turbulent boundary layer developing over such surf...

The effect of spanwise heterogeneous surface geometry on the turbulent boundary layer secondary flows and on skin friction is investigated experimentally. The surfaces consist of smooth streamwise-aligned ridges of different shapes and widths with spanwise wavelengths comparable to the boundary layer thickness ($S/\delta \approx \mathcal{O}(1)$). C...

An experimental investigation of a turbulent boundary layer flow over a heterogeneous surface is carried out to examine the mean flow and turbulence characteristics, and to document the variation of skin-friction that might aect the applicability of traditional scaling and similarity laws. The heterogeneity is imposed along the spanwise direction a...

The effect of the Strouhal number on periodic forcing of the flow over a backward-facing step (height, $H$) is investigated experimentally. Forcing is applied by a synthetic jet at the edge of the step at Strouhal numbers ranging from $0.21<St_H<1.98$ ($St_H = f H/U_\infty$) at a Reynolds number of $Re_H = HU_\infty/\nu = 41000$. In the literature,...