Computational Fluid Dynamics is about solving difficult engineering problems, using expensive software, enormous computing resources and highly trained engineers. If the problems weren't difficult, or very important, then it is doubtful that anyone would devote so much effort, time, and money at solving them. From the perspective of a modern engineer, it would be easy to assume that this desire to apply simulation technology complex problems is a recent concern; that only today are we able to contemplate solving tough industrial problems, armed with a complex array of multi-physics simulation tools.