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Description: |
Turbulence in diffuse gases (e.g., interstellar gases) can have Reynolds numbers of the order of 107 or even larger. The source of such turbulence are point like explosions with energies of the order of 1051 erg that stir the medium continuously. Such turbulence decays on a time scale of the order of a sound crossing time and becomes subsonic due to the dissipation of energy through shocks. Contrary to what is expected from the Kolmogorov (1941) theory there is dissipation of energy (up to some 20%) in the inertial range.
In this talk I shall discuss the block mesh refinement algorithm (BMR) that we use in 3D HD and MHD simulations of supersonic turbulence. BMR is a scheme that implements grid refinement on the fly, both in time and space in a parallel fashion, such that a minimum number of blocks and cells is needed to provide the most complete description of the turbulent flow allowing the full length scale coverage from the injection to the viscous scales. At the higher BMR levels subgrids start covering smaller and smaller fraction of the whole volume that scales with the Reynolds number as Re-1/4. This scaling is consistent with the fractal dimension of the most dissipative structures in both HD (e.g., shocks) and MHD (e.g., shocks and current sheets) supersonic turbulence.
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Date: |
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| Start Time: |
14:30 |
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Speaker: |
Miguel A. de Avillez [Department of Mathematics, University of Evora (Portugal) and Institut of Astronomy, University of Vienna (Austria)]
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Place: |
Room 5.5
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| Research Groups: |
-Numerical Analysis and Optimization
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See more:
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