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The present study aims to investigate the effects of the several rear slant angles, φ = 25°, 30°, 32°, 33° and 35°, on the wake characteristics downstream of the Ahmed body because the angle of the rear window plays an important role in the flow characteristics. This work presents numerical simulations using ISIS-CFD flow solver which is developed by Centrale Nantes and CNRS. The turbulence model used is an hybrid RANS-LES model: the Improved Delayed Detached Eddy Simulation (IDDES). Detailed discussions of the flow features are provided using time-averaged streamlines, vorticity contours, turbulent kinetic energy contours and an iso-surface of l2. Drag and lift coefficients are also presented. In the symmetry plane, three critical flow points, which correspond to foci of separation and saddle point in the wake of the Ahmed body, and the focus of separation over the slanted surface are presented.

This paper focuses on the numerical simulations of flow around a realistic generic car model called the DrivAer body. This new open-source model is based on the geometries of two medium sized cars, the Audi A4 and the BMW 3 series, and possesses more representative car features as the well-known generic Ahmed body. In this paper, only the fastback geometry is investigated. The flow solver used is ISIS-CFD developed by CNRS and Ecole Centrale de Nantes. This solver is based on a finite-volume method, and two turbulence modelizations are used: the Explicit Algebraic Reynolds Stress Model (EARSM) and a Detached Eddy Simulation (DES). Two meshes are used. For one, the walls are described with a wall function and the mesh contains 19 million cells. This mesh is called “Mesh 1”. For the second mesh, a low-Reynolds number turbulence model for the walls is used. In this case, the mesh contains 39 million cells, and is called “Mesh 2”.

This paper presents simulations for the prediction of the flow around a passenger vehicle. The flow solver used is ISIS-CFD developed by the Numerical Modeling Group of the Fluid Mechanics Laboratory of Ecole Centrale de Nantes. The CFD simulation is carried out with the Explicit Algebraic Stress Model (EASM) turbulence model. For improved precision, the recently developed automatic adaptive grid refinement procedure of the flow solver is used. This procedure is built for unstructured hexahedral grids and naturally supports both isotropic and anisotropic grid refinement to keep the grid sizes small for 3D simulations. The refinement criterion used to indicate the locations of grid refinement is based on the second spatial derivatives of the pressure. This criterion is efficient for flows with strong local vorticity. Three models are used to validate this approach: the Ahmed model, the Willy model and a pickup truck model.

This paper presents a finite-volume-based detached-eddy simulation for the prediction of flow around a passenger vehicle. The flow solver used is ISIS-CFD developed by the CFD Department of the Fluid Mechanics Laboratory of Ecole Centrale de Nantes. The validation is carried out by a crosswind simulation around the squareback Willy model. The model was designed in order that separations are limited to the region of the base for a moderate yaw angle. This model without sharp corners on the fore body and a square base is more convenient for the analysis of unsteady separations limited on its leeward side and base. The angle between the upstream velocity and the direction of the model varies between 0° and 30°. The results are compared to a previous numerical study obtained with a RANS simulation and experimental data.

The objective of this research is to improve the understanding of unsteady three-dimensional separated flows on bluff bodies. This research focuses on the analysis of the instability and safe maneuverability of passenger vehicles associated with unsteady atmospheric crosswind conditions. Experimental and numerical analysis were performed on the squareback Willy car model animated by an oscillating yaw angle in a steady wind. Experiments were carried out at a Reynolds number of 0.9 106, a frequency of 2 Hz, with an amplitude of Δβ = 10° at the Conservatoire National des Arts et Metiers (CNAM). Unsteady wall pressures were obtained with sensors located inside the model. Computations were performed at the Ecole Centrale de Nantes (ECN). The ISIS-CFD flow solver, developed by the CFD Department of ECN, used the incompressible unsteady Reynolds-Averaged Navier-Stokes equations. Experimental and numerical comparisons are completed with numerical simulations at a larger yaw angle.

The general objective of this research is the analysis of the instability of passenger vehicles associated with transient crosswind gusts. Experimental and numerical tests are performed on the squareback Willy test model, which is realistic compared to a van-type vehicle. Experiments were carried out in a semi-open test section at the Conservatoire National des Arts et Métiers (CNAM) and computations were performed at the Ecole Centrale de Nantes (ECN). The ISIS-CFD flow solver, developed by the CFD Department of the Fluid Mechanics Laboratory of ECN used the incompressible unsteady Reynolds-averaged Navier-Stokes equations. The experimental results obtained at a Reynolds number of 0.9 106 were compared with numerical data for steady flow. Agreement between experimental and computed aerodynamic forces, wall pressures, and tomographies of total pressure is fairly good.