Faced with a choice between calculation methods that are simple but limited or methods that are more elaborate but costly, some choose... not to choose. By combining the two approaches, they are attempting to model complex phenomena with the greatest possible precision.

An aircraft carried by air always leaves behind it a wake consisting of vortices, the power of which increases with the mass of the aircraft. In this plan perpendicular to the aircraft path, the largest vortices were generated at the wingtips. The slats and flaps deflected in takeoff phase are the source of the smallest structures.

The air deforms the structure of an aircraft, while the aircraft's vibrations modify the air flow. To take all of these phenomena into consideration, ONERA is developing models coupling fluid mechanics and solid mechanics.

Ceramics have been a little neglected recently but they still have something to reveal to us: the latest generations of eutectic" ceramics are very promising for engines, while ceramic composites – more traditional – have had a new lease of life with the development of low-cost processes.

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The pilot of an aircraft is sometimes compelled to proceed to an emergency landing. According to the reasons and the circumstances, secured landing procedures are imposed to him. For instance he can have to land wheels up".

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This image was obtained from a quadri-lateral shift interferometer1 for analyzing a light beam exhibiting a defect very well known to opticians: spherical aberration.

When trying to miniaturize optical instruments to the utmost, the physical phenomena that come into play become complex, fascinating and particularly interesting. Welcome to the world of nanophotonics.

Generally, numerical simulation of flows provides decision assistance elements: for design, dimensioning, prediction of operation. It has become very reliable because it is based on theoretical foundations and models perfected after basic physical experiments and validations under realistic operating conditions.

This is an original quasi-optical device, designed to divert a beam which is electromagnetic and not light, for example X-band radio waves. No mechanical movement. It’s controlled by varying the properties of a rather special lens – made of plasma – a material state constituted of ions and electrons with very particular properties.