Free Decay of Turbulence and Breakdown of Self-Similarity
نویسنده
چکیده
It has been generally assumed, since the work of von Karman and Howarth in 1938, that free decay of fully-developed turbulence is self-similar. We present here a simple phenomenological model of the decay of 3D incompressible turbulence, which predicts breakdown of self-similarity for low-wavenumber spectral exponents n in the range nc < n < 4, where nc is some threshold wavenumber. Calculations with the eddy-damped quasi-normal Markovian approximation give the value as nc ≈ 3.45. The energy spectrum for this range of exponents develops two length-scales, separating three distinct wavenumber ranges.
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