Free Turbulence, Bounded Turbulence, and Universal Theories

In 1941, Kolmogorov enunciated a universal theory of fluid turbulence according to which the energy spectrum of homogeneous and isotropic flows exhibit k^{-5/3} energy spectrum. Though many experiments and simulations verify the above law, the theory is not applicable in the presence of additional forces or walls. We will show in this talk that the buoyancy-driven stably-stratified flows show k^{-11/5} spectrum. In the thermally-driven turbulence, the velocity field follows Kolmgorov’s law, and the thermal plates have profound influence on the temperature spectrum. Rotation makes major part of a turbulent flow laminar. Thus, Kolmogorov’s universal theory of turbulence is not so universal when additional forces or walls are introduced.