DIFFUSION DUE TO RANDOM WAVES

Abstract

The knowledge of the physical processes of oceanic mixing has been advanced in the last decade owing to enormous efforts by both scientists and engineers in this field. Nevertheless, it is far from completion. In this paper the effect of random waves on oceanic mixing is specified. The author described in a preceding investigation that the linearized random waves had no diffusivity due to the basic condition of the covariance stationary, second order stochastic process. The analysis is extended up to the third-order approximation including wave-wave interactions. Turbulent diffusion coefficient is given in terms of wave spectra.Derived diffusion coefficient is classified into two regions. In one region diffusion coefficient D is linearly proportional to time elapsed after the release of dye patches. In the other region D is constant. The criterion between these two regions is the interaction time of random waves. However, precise description of the interaction time is not sufficient because of relatively poor knowledge of wave-wave interactions.The magnitude of the theoretically derived diffusion coefficient is compared with that observed in ocean and in a wave tank. It is a subject of further study to perform experiments under the same conditions as those assumed in the theory.