Abstract
Time variations of the hydrodynamical system were followed by numerical process using the non-divergent barotropic vorticity equation.
It was found that, in a fluid system, the kinetic energy initially tends to flow into the component of larger scale, and the mean flow kinetic energy oscillates with respect to time with a definite period.
The period of the oscillation of energy thus computed was compared with the analytic solution of a simple non-linear hydrodynamical system. The solution seems to explain some features of the fluid qualitatively.
A numerical example of the system which has a close resemblance to the situation observed in the middle layer of the atmosphere was followed for 20-day period. It was found that the kinetic energy of the mean flow was supplied by the existing disturbance through the barotropic process.
