Abstract
The intermittency of an incompressible passive vector convected by homogeneous isotropic turbulence is studied by comparison with that of the velocity and passive scalar. This is used to explore the physics underlying the differences in statistical properties between the velocity vector and passive scalar. Direct numerical simulations with grid points of and two types of forcing method are performed at Reynolds numbers of , 300, and 400. It is found that the probability density function (PDF) of the passive vector is wider than Gaussian. The PDFs of the logarithm of the dissipation rates of the kinetic energy, for the velocity and passive vector, are close to each other and well approximated by the log-normal distribution. Unlike the pressure PDF, which is negatively skewed, the PDF for the pseudopressure is nearly symmetric. Visualization results show that the pseudoenstrophy for the passive vector is close to sheetlike, similar to the case of the passive scalar, while the enstrophy is tubelike. The scaling exponents of the passive vector moments are found to be anomalous, nonuniversal at high order, and intermediate between the velocity and passive scalar for the order . The pseudopressure tends to reduce the extreme events, while the linearity of the fundamental equation leads to stronger intermittency.
7 More- Received 15 May 2019
DOI:https://doi.org/10.1103/PhysRevFluids.4.114602
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