Fluid mechanics

Toys and fluid mechanics

I visited my 10 year old nephew this week for the the first time in a year (I’m not avoiding him – we live on opposite sides of the the world).  His tia and I gave him several presents, most of them educational as well as fun (naturally!). Lego tends to be his toy of choice but this time we  included a rubber bands vehicles set. It’s great!! My nephew made the aeroplane (one of several options) and, rather embarrassingly,  was much batter at it than me (even though the instructions were written in a language he doesn’t understand). My practical engineering skills may not be as sharp as a 10 year old’s, but at least I could talk to him about the mathematics of flight and airfoil theory.

Elastic band powered plane: built by my nephew

My nephew is very bright but, to be honest, I think I went too far with the Milne-Thomson Circle Theorem! But it’s been a while since I last studied and taught inviscid flow theory and viscous boundary layers – perhaps I got a little over excited!

This is such a wonderful example of applied maths: beautiful theory combined with powerful applications. ODEs and PDEs, Cauchy-Riemann and conformal mappings, asymptotics and separation…and then there’s CFD! I even think the common misconceptions/misinterpretations of Bernoulli’s principe, although sometimes frustrating, add a little extra spice to the matter.  What a great subject to start studying as an undergraduate mathematician…or a 10 year old Lego enthusiast.

Experiment is the acid test for theory and I’m pleased to say that this plane took off smoothly from the dinning room table, glided elegantly through the patio doors…and off the balcony of the first floor flat before an ungraceful fall to Earth. Fortunately, it lives to fly again.