Kraichnan 



Fig. 1 - Eddy diffusivity found from numerical experiment (dots) 

 and the direct-interaction approximation (solid curve) for the energy 

 spectrum of Eq. (9b) 



Fig. 2 - Lagrangian velocity correlation found from nunneri- 

 cal experiment (dots) and the direct-interaction approxima- 

 tion (solid curve) for the energy spectrum of Eq. (9b) 



792 



