VMS- and OES-based hybrid simulations of bluff body flows

International audienceFlows past bluff bodies show turbulent near wall behavior in various conditions. For example, for a high Reynolds incident flow, the boundary layer at front side of a circular cylinder may show a transition to a turbulent boundary layer. After separation, the back of the cylinder is in contact with the turbulent wake. Analogously, the turbulent wake of a first obstacle can hit the front of a second one

Dynamic Effect of an Active Deformable Flat Plate on Its Turbulent Flow

Updated contributions reflecting new findings presented at the ERCOFTAC Symposium on Unsteady Separation in Fluid-Structure Interaction, 17-21 June 2013, St John Resort, Mykonos, GreeceThis paper addresses the topic of the influence of the profile of a plate on a turbulent flow. The study is based on numerical results obtained by URANS and hybrid (DDES) turbulence modeling and compared with experimental results. The flat plate has an aspect ratio of 20 (length over thickness) and the edges are not smoothed. The plate includes Shape Memory Alloys (SAM), which allows it to arch under the effect of an electric voltage. The deformation by the material corresponds to a beam deformation and is implemented in the numerical simulation according to this definition. The Reynolds number is Re=200,000 , which led to a turbulent flow with a Von Karman vortex shedding and Kelvin Helmotz instabilities in the shear layer. The simulations are performed with several turbulence models: k- ϵ-OES, k-ω-BSL-OES, k-ω-DDES-BSL-OES, k-ω-DDES-SST-Menter. These models are used in a first step to determine the three-dimensional flow around the plate plane inclined by 10∘ . The behavior of the flow are found similar between experiment and numerical simulations. The purpose of the curve shape by deformation is then compared to a linear form by rotation of the plate. The curved shape provides the same lift coefficient with less required deformation and thus with a lower drag coefficient and also a lower frequency. The dynamic deformation is slow compared to the freestream velocity, it weakly affects the coefficients and frequencies compared to linear shape

MORPHING FOR SMART WING DESIGN THROUGH RANS/LES METHODS

This article presents numerical simulation results obtained in the context of the H2020 European research project SMS, “Smart Morphing and Sensing for Aeronautical configurations” by using among other, hybrid RANS-LES methods, able to accompany the design of the wings of the future. The morphing concepts studied are partly bio-inspired and are able to act in multiple time and length scales. They are proven efficient for the increase of the aerodynamic performances of A320 wings in reduced scale and near scale one, in synergy with the prototypes built within this project. The simulations have shown the ability of novel electroactive actuators performing slight deformation of the trailing edge region and optimal vibrations, to create suitable vortex breakdown of specific coherent structures and to enhance beneficial vortices, leading to thinning of the shear layers and the wake’s width. The simulations quantified the optimal actuation ranges and the gains in lift increase, drag reduction and simultaneous attenuation of the noise sources past the trailing edge