Abstract
The decay of enstrophy in two-dimensional turbulence at high Reynolds number is one of important issues of study of two-dimensional turbulence. Up to now, many laws of enstrophy decay have been proposed. Recently, Yakhot and Wanderer (2004) pointed out from numerical simulations the existence of different regimes of enstrophy decay in two-dimensional turbulence. During the initial stage, the magnitude of the decay exponent of enstrophy is about 0.7. In the late stage, it is about 0.4, which is well known the decay exponent and is explained by the vortex scaling theory of Carnevale et al (1991). Yakhot and Wanderer (2004) conjectured that this transition of decay exponent of enstrophy is responsible for finite-size effect. We perform numerical simulations to examine their conjecture. However, our simulations do not support their conjecture. We also analyze the results of our numerical simulations from the view point of the vortex scaling theory and discuss the transition of the decay exponent of enstrophy.