THE MICROSTRUCTURE OF TURBULENT FLOW*

In 1941 a general theory of locally isotropic turbulence was pro-posed by Kolmogoroff which permitted the prediction of a number of laws of turbulent flow for large Reynolds numbers. The most ~portant of these laws, the dependence of the mean square of the difference in vel-ocities at two points on their distance and the dependence of the coef-ficient of turbulence diffusion on the scale of the phenomenon, were obtained by both Kolmogoroff (references 1 and 2) and Obukhoff (ref-erence 3) in the same year. At the present time these laws have been experimentally confirmed by direct measurements carried out in aero-dynamic wind tunnels in the laboratory (references 4 and 5), in the. atmosphere (references 6 and 7), and also on the ocean (reference 8).1 In recent years in the Laboratory of Atmospheric Turbulence of the Geophysics Institute of the Soviet Academy of Sciences, a number of investigations have been conducted in which this theory was further developed. The resul~s of several of these investigations are pre-sented in this paper. The fundamental physical concepts which are the basis of Kolmogoroff's theory may briefly by summarized as fo11ows. 3 A turbulent flow at large Reynolds numbers is considered to be the result of the imposing of disturbances (vortices or eddies) of all possible scales of *"Mikrostructura turbulentnogo potoka, ~ Prikladnaya Matematika i Mekhanika, Vol. XV, 1951, pp. 3-26. ~he applications of these laws to certain problems of the physics of the atmosphere may be found in references 9 and 10. 2In addition to the results contained in the present article, ref-erence may also be made to the theoretical investigation of the struc-ture of the temperature field (or of the concentrations of any neutral additive) in the turbulent flow, presented in references 11 and 12. The applications of the latter results may be found in references 13 and 14. 3For a more detailed presentation see reference 15