Reynolds number effects on the turbulent mixing of passive scalars

The effects of the Reynolds number Re of the advecting turbulent flow on the small-scale properties of passive scalars fields are studied numerically for the case of Schmidt numbers Sc larger than unity. The deviations from local isotropy as quantified by odd-order derivative moments are found to decrease. The intermittency of the scalar gradient and dissipation rate fields is measured by the fourth order derivative moment and the multifractal formalism, respectively. Both analysis methods indicate an increasing small-scale intermittency of the mixing for increasing Re at fixed Sc.