Modification of turbulent helical/nonhelical flows with small-scale energy input
| Autor: | Yasutaka Nagano, Yuji Suzuki |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Fluid Flow and Transfer Processes
Physics Turbulence K-epsilon turbulence model Mechanical Engineering Computational Mechanics Turbulence modeling K-omega turbulence model Mechanics Condensed Matter Physics Helicity Physics::Fluid Dynamics Classical mechanics Mechanics of Materials Energy cascade Turbulence kinetic energy Wavenumber |
| Zdroj: | Physics of Fluids. 11:3499-3511 |
| ISSN: | 1089-7666 1070-6631 |
| Popis: | Modification of helical/nonhelical turbulence by adding small-scale turbulence is investigated with the aid of direct numerical simulations of isotropic turbulence. Detailed characteristics of the energy and helicity spectral transfer were examined. It is found that nonlocal energy cascade through isosceles triads toward the wave-number range of the energy input is markedly enhanced, thus the turbulent intensity is decreased faster than a flow field with no energy input. The optimum wave number for turbulence reduction depends only on the characteristic wave number of the energy-containing range, once the magnitude of the energy input is given. A model equation for isosceles triads derived from the EDQNM approximation indicates that the optimum wave number increases with increasing energy ratio between the energy input and the parent turbulence. For helical turbulence, the sign of helicity is crucial for the helicity and energy transfer as well as the decay rate. When the helicity of small-scale energy in... |
| Databáze: | OpenAIRE |
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