OCEANOGRAPHY IN THE UNITED STATES 279 



made by Dr. von Arx, are meant to exhibit realistic circulation pat- 

 terns as they might appear from a very high altitude above the real 

 oceans on a very clear day. Other rotating basins do not bear any 

 recognizable similarity to the earth but are used in checking and veri- 

 fying theoretical studies. Experiments in rotating basins can be con- 

 trolled and conditions varied. In the real ocean, of coui-se, we simply 

 have to measure things as they are — even this is a difficult task — and 

 there is no immediate possibility of controlling or changing the ocean 

 circulation to check our theories. 



Theoretical considerations enter into the work of many people at 

 Woods Hole other than those who make it their primary concern. In 

 order to illustrate what is being done here I will conclude with one 

 outstanding example — the work of Drs. Malkus and Veronis on the 

 theory of turbulence. 



You have all noticed how there are, in nature, two kinds of fluid 

 flow : laminar flow and turbulent flow. A thick oil, poured slowly out 

 of a bottle, flows in a laminar fashion. Each particle moves in a smooth 

 curve or trajectory. If the fluid is thin and poured quickly there are 

 many eddies and irregular motions — we call such flow turbulent. A 

 theoretical understanding of turbulence is very important for all kinds 

 of practical things besides oceanography ; for example, in the design 

 of aircraft and ships. Because there has never been a sufficiently gen- 

 eral theory of turbulence, engineers have had to employ large and ex- 

 pensive wind tunnels and towing tanks to obtain the necessary infor- 

 mation to allow for turbulence when designing new aircraft and ships. 



Now that engineers are planning nuclear rockets and investigating 

 the hydrodynamics of plasma in thermonuclear reactors, the need for 

 a basic theoretical understanding of turbulence is once again being 

 felt. Ten years ago Dr. Malkus set himself the ambitious task of 

 working out a basic theory of turbulence, and when he began there 

 were several of us who thought he had bitten off quite a bit more than 

 he could chew. After all, it is a field in which many great scientists 

 over the past 50 years have made such very limited progress that 

 they soon turned to other subjects. But Malkus, by a series of re- 

 markable insights, has succeeded in paving the way to a general theory 

 of turbulence. Already he has been able to deduce theoretically many 

 of the features of fluid flow which hydraulic engineers have previously 

 had to discover by tedious and expensive experiment. ^luch remains 

 to be done, but engineers, astrophysicists, rocket designei's, and others 

 besides meteorologists and oceanographers are beginning to take a deep 

 interest in his work. That he is contented to stay at Woods Hole, 

 despite offers fi-oni industry, is a measure of how much he values the 

 freedom of inquiry which he enjoys here. 



What I mainly want to convey to you is the diversity of the theoret- 

 ical studies that are miderway here : theories of specific oceanographic 

 phenomena such as ocean currents, of more general hydrodynamical 

 problems involving rotating fluids, and very general investigations 

 like Malkus' theory of turbulence which is of interest to all areas of 

 science where liquids are involved. 



Mr. Chairman. And next will be Miss Joanne S. Malkus. 



