Compressibility effects on the scalar mixing in reacting homogeneous turbulence

The compressibility and heat of reaction influence on the scalar mixing in decaying isotropic turbulence and homogeneous shear flow are examined via data generated by direct numerical simulations (DNS). The reaction is modeled as one-step, exothermic, irreversible and Arrhenius type. For the shear flow simulations, the scalar dissipation rate, as well as the time scale ratio of mechanical to scalar dissipation, are affected by compressibility and reaction. This effect is explained by considering the transport equation for the normalized mixture fraction gradient variance and the relative orientation between the mixture fraction gradient and the eigenvectors of the solenoidal strain rate tensor.Comment: In Turbulent Mixing and Combustion, eds. A. Pollard and S. Candel, Kluwer, 200

Phonon polariton study of CuCl1-x Brx

Journal ArticleThe optical-phonon spectrum of CuCI-x Brx at low temperature is very unusual in regard to many of its properties. Despite the apparent two-mode behavior our measurements illustrate anomalies in the Raman intensity and temperature-induced frequency shift, as well as in the oscillator strengths yielded by the polariton measurements. All these irregularities are connected to the anomalies of CuCI and they disappear rapidly with increasing Br concentration. The data are interpreted in terms of a previous model, which allows copper ions to occupy off-center sites. It is assumed that in CuC1xBrx this may happen only in the tetrahedra where Cu+ is surrounded by chlorine ions alone

A STUDY OF POLARITONS AND PHONON PECULIARITIES IN CuCl1-xBrx

The optic phonon anomalies found in CuC11-xBrx by means of Raman scattering and polariton measurement are presented. These irregularities are explained in terms of a model which accounts for the phonon and other anomalies in pure Cu-halides