E321 成層乱流のスペクトル LES

概要

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A spectral large-eddy simulation of forced uniformly stably stratified turbulence is performed in the periodic boundary box domain with 512^3 grid points. Brunt-Vaisala frequency N is set in the parameter region for the fine scale (O((10)^0)∿O((10)^2)[m]) ocean turbulence. It is assumed that the subgrid scale flow is nearly isotropic fully developed turbulence and the spectral eddy viscosity and diffusivity are estimated from the Lagrangian renormalized approximation (LRA) theory. The vertical shear speetrum from the simulation is compared with that of a mesurement in the ocean. The energy densities in wavevector space are concentrated around the vertical axis for all modes (vortex, wave, and potential). The energy densities along the vertical (k_■) axis and the horizontal (k_h) axis approximately scale as k_■^<17/3> and k_h^<8/3>, respectively, Evaluation of the eddy viscosity and diffusivity for larger grid scale is also discussed.
日本流体力学会の論文
2001-07-31