Cambridge University Press, Journal of Fluid Mechanics, (741)
DOI: 10.1017/jfm.2014.1
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AbstractIn this work, the scaling statistics of the dissipation along Lagrangian trajectories are investigated by using fluid tracer particles obtained from a high-resolution direct numerical simulation with $\mathit{Re}_{λ }=400$. Both the energy dissipation rate $ε $ and the local time-averaged $ε _{τ }$ agree rather well with the lognormal distribution hypothesis. Several statistics are then examined. It is found that the autocorrelation function $ρ (τ )$ of $\ln (ε (t))$ and variance $σ ^2(τ )$ of $\ln (ε _{τ }(t))$ obey a log-law with scaling exponent $β '=β =0.30$ compatible with the intermittency parameter $μ =0.30$. The $q{\rm th}$-order moment of $ε _{τ }$ has a clear power law on the inertial range $10<τ /τ _{η }<100$. The measured scaling exponent $K_L(q)$ agrees remarkably with $q-ζ _L(2q)$ where $ζ _L(2q)$ is the scaling exponent estimated using the Hilbert methodology. All of these results suggest that the dissipation along Lagrangian trajectories could be modelled by a multiplicative cascade.