Correction to the four-fifths law due to variations of the dissipation

The full Kolmogorov equation is analyzed with respect to Galilean invariance. It is shown that the time-dependent term in typical applications as jets and wakes will cause rather large deviations from the four-fifths law, even at fairly large Reynolds numbers. With the use of the K - epsilon-model an inertial range model expression is derived for the third-order structure function of freely decaying turbulence at finite Reynolds number. The expression is compared with results from previously reported experiments. It is argued that experiments to test intermittency corrections to the Kolmogorov 1941 theory should be made in flows which are both stationary and homogeneous in the mean flow direction, such as pipe and channel flows. (C) 1999 American Institute of Physics. [S1070-6631(99)00803-X].