Rodolphe Perrin

Near-Wake Turbulence Properties around a Circular Cylinder at High Reynolds Number

The present study investigates the turbulent properties of the flow around a circular cylinder in the near-wake and in the near-wall upstream region at the Reynolds number 140,000. A detailed cartography of the mean and turbulent velocity fields using a moderate blockage and aspect ratio is provided in order to use the present results for direct comparisons with realisable 3D Navier-Stokes computations. The flow structure is analysed by means of two experiments using respectively the LDV and the PIV techniques, both providing a refined grid of measurement points. The dynamics of the separation region, the growth and decay of turbulence in the near wake, as well as the spatial growth of the organised mode are analysed.

Demonstration of Improved DES Methods for Generic and Industrial Applications

This paper presents an overview of the DES methods implemented at the Institute of Fluid Mechanics and Engineering Acoustics (ISTA) at the TU-Berlin during the course of the European DESider project. As well as the validation of these methods on the basis of simplified, academic flow cases presented in the first part, their suitability and necessity for complex industrial applications is demonstrated using results from other research projects. The methods prove robust and reliable for a wide range of applications, ranging from external to internal flows, from bluff bodies with massive separation to the partial resolution of attached boundary layers.

Anisotropic eddy-viscosity concept for strongly detached unsteady flows

The accurate prediction of the flow physics around bodies at high Reynolds number is a challenge in aerodynamics nowadays. In the context of turbulent flow modeling, recent advances like large eddy simulation (LES) and hybrid methods [detached eddy simulation (DES)] have considerably improved the physical relevance of the numerical simulation. However, the LES approach is still limited to the low-Reynolds-number range concerning wall flows. The unsteady Reynolds-averaged Navier–Stokes (URANS) approach remains a widespread and robust methodology for complex flow computation, especially in the near-wall region. Complex statistical models like second-order closure schemes [differential Reynolds stress modeling (DRSM)] improve the prediction of these properties and can provide an efficient simulationofturbulent stresses. Fromacomputational pointofview, the main drawbacks of such approaches are a higher cost, especially in unsteady 3-D flows and above all, numerical instabilities.

Joint Numerical and Experimental Investigationof the Flow Around a Circular Cylinder at High Reynolds Number

A collaborative study is presented for the flow past a circular cylinder at high Reynolds number, which makes use of both experimental and numerical approaches. The case setup was designed specifically to maximize the level of comparison between experiment and simulation, incorporating a confined environment enabling simulation on a domain of moderate size and avoiding problems associated with “infinite conditions”. The two principle goals of the investigation are the detailed validation of the simulation using the experiment and vice versa and the exploitation of the respective advantages of both approaches in order to provide a better understanding of the dynamics of the flow. The experiment was carried out using PIV, stereoscopic PIV and time-resolved PIV, and the simulation was performed using detached eddy simulation (DES), a hybrid method for turbulence treatment. A very good agreement between the simulation and the experiment is achieved for the steady mean motion, the coherent motion and the turbulence quantities. In the analysis, the experiment and simulation are shown to be complementary and to allow a more complete description of the flow studied.