The mathematical description of the behaviour of typical fluids, like water at room temperature, was one of the great scientific breakthroughs of the 19th century. Understanding and applying the equations that describe these fluid drove many developments in mathematics for the next 100 years. Later, with the advent of modern computing, new fields of mathematics emerged devoted to designing algorithms to simulate these flows. This simulation capability has revolutionised many fields of engineering: no car, aeroplane, bridge, or stent is built without it.