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Aero hydro

We provide tailored engineering services in the aerodynamics of land-based and aerospace vehicles, including propulsion. Similar services are offered in the context of hydrodynamics of ships and amphibian structures, sails aerodynamics, etc. We help design automotive exterior concepts with pre-design or detailed underbody, with complete vehicle aerodynamics analysis, extending the simulations to HVAC systems, etc. This area of investigation is also conducted for the design of ships and submarines, requiring advanced turbulence models combined with smart meshing techniques. Be it for land, sea or space vehicles, TransAT is systematically employed using a hierarchical problem-oriented strategy: from RANS turbulence models to high-fidelity LES and V-LES approaches on scalable HPC systems.

Land based vehicles

Grid generation in CFD is known to require up to 70% time of the simulation process. Although unstructured grids have somewhat helped invert the tendency these techniques still need to be coupled to structured BFC meshes for the boundary layer. The IST/BMR functionality of TransAT has solved the grid generation problem for external flows, whereby all sorts of geometries are mapped into a Cartesian grid. Land-based aerodynamics problems are now solved (in 3D) very simply. Apart from meshing, transient resolved-scale simulations (LES, DES, V-LES) are now acknowledged to deliver valuable flow information that are critical for the design, including vortex shedding, unsteady loads, etc.

Aerospace vehicles

The aerodynamics of space aircrafts precedes in general other engineering studies, since it directly serves the analysis of structural integrity, stability, performance and store trajectory of the vehicle. Fighter jets are designed to carry stores under the wing, which may affect the flow on the surrounding components such as the horizontal tail and the vertical stabilizer, including changes in drag and lift forces, flow separation and surge. Controllability and stability of the aircraft may thus be altered. Modern CFD tools should be capable to analyze
the perturbations to the flow that could be brought by the carried stores, but two main key issues need to be resolved first: efficient, fast grid generation combined with advanced turbulent flow simulation using scale resolving techniques (LES and V-LES) that are amenable to predict the detached eddy structures from/around the surrounding components.

Yacht sails aerodynamics

Flow in yacht sails is complex, in particular in the Genoa; sailing downwind is a simpler flow problem to model. But various issues are still open, such as the prediction of the leading edge separation of both sails, the re-attachment of the boundary layer downstream, the trailing edge separation on the suction side of the Genneker because of the retarding pressure gradient. TansAT solves these flows in an unsteady manner (LES or V-LES) in order to provide as faithful picture of real sea conditions.

Submarine hydrodynamics

CFD has also been employed to predict the flow past submarines, with the objective to determine the forces and moments on the hull in order to improve manoeuvring predictions, for different wave and sea-surface conditions. While early simulation campaigns were focusing on the flow structure, in particular the vertical structure in the wake field, and their interaction with the hull, today design engineers are interested to learn about the vessels hydrodynamics while operating near the free surface. Be it for sub-sea or at surface, real design improvements have been achieved in this area thanks to modern CFD. But here, too, TransAT turns out to be efficient, for its immersed surfaces meshing technology which minimizes user interaction, the scale-resolving strategies for turbulent high-Re flows, and the interface tracking techniques such as the level-set method, required for wave-hull interactions.

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