Actually, there is an intrinsic reason we don't have a theory of viscous flows. Classical mechanics is much easier, although the math gets very hard when you have even three bodies in play (hence the "three body problem"). The underlying insights are simple, but the application is desperately hard. With fluid mechanics, we are still largely clueless. We can't even write down most of the equations, except in a sort of empirical, phenomenological sort of way. Fluid mechanics has little predictive power. There is no deep theory analogous to classical mechanics. I gather that since I stopped doing this stuff there has been progress made using chaos theory. But if girls had started doing physics with an intense interest in viscous flows, they would have faced the same problems. I suppose they might have invented chaos theory earlier, but you still need calculus to do that, and Newton incvented calculus to do classical mechanics (Leibniz invented it at the same time for fun). --jks _____________________________________________________________________________________ Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com