Abstract: Taking vorticity equation as a controlling equation, we simulate three vortexes developing progress with initial condition of Gaussian probability vorticity distribution. The wavelet expression of vorticity contains scaling coefficient term and wavelet coefficient tenn. The latter can be divided into a significant wavelet coefficient term and a trivial wavelet coefficient term reference to a given critical value. The critical value contains practical flow information. The vorticity is reconstructed only with scaling coefficients and significant wavelet coefficients. It saves computing time and capture most part of entrophy. Numerical results show that scaling coefficients together with significant wavelet coefficients is less than 10% of total wavelet coefficients, but they contains more than 99% of total enstrophy.

Key words: wavelet adaptivity, vorticity equation, vortex emerge, coherent structure, critical value