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ISSN オンライン: 2642-0554

IMPLEMENTING SCHMIDT NUMBER DEPENDENCE IN A STOCHASTIC LAGRANGIAN MODEL FOR THE SCALAR GRADIENT

Michel Gonzalez
CNRS, UMR 6614, Laboratoire de Thermodynamique, CORIA, Site universitaire du Madrillet, 76801 Saint-Etienne du Rouvray, France

要約

A stochastic Lagrangian model for the scalar gradient (Gonzalez, 2009) is extended to Schmidt numbers larger than unity as a necessary step to make the approach valid for a wider range of mixing problems. The basic idea is to derive the damping time scale of the modelled molecular diffusion from the phenomenology of stretched scalar layers. In this context, the diffusive damping rate is itself given by a non-linear stochastic equation. Although the model has to be checked further and improved in some respects − for instance, as regards the scaling of the scalar gradient intermittency with the Reynolds number −, first results in isotropic turbulent flow agree with the standard physics of scalar turbulence.