Definition of Computational fluid dynamics

Any material which flows, such as air or water, can be referred to as a fluid; ‘dynamics’ simply means moving and ‘computational’ is about calculations. Aerodynamics was for many years about observing the air flow over a vehicle, with sample calculadesign. This means that there is now no longer a need to make a buck, or a mock-up, of a car to be able to visualize the design. As an example, vehicle body engineers used to use a wooden buck of an engine to help them to design the body work, and see if it could be fitted to and removed from the initial body design. The Rover 75 is the first car to be designed without this; a solid modelling package was used for a virtual engine and body design, allowing an onscreen test fit.
Having designed the virtual car it is possible to observe it in a virtual wind tunnel and carry out calculations both internally and externally, this is what computational fluid dynamics (CFD) is all about. As you can appreciate, the cost of a virtual design and aerodynamic testing without a wind tunnel is only a fraction of the cost of building a buck and using a real wind tunnel.