Energy Transfer in Nearly Isotropic Perforated-Plate Turbulence

In this empirical study, the turbulence energy transfer is quantified downstream of a novel orificed perforated plate in a wind tunnel. The measurements were taken within the nearly homogeneous and isotropic region in which the turbulence statistics up to the 4th order were measured to be fairly uniform. The three-dimensional turbulence spectra were estimated from their one-dimensional counterparts and the evolution of the turbulence energy transfer was characterized.

PGSE-NMR & Sans from TPB Based Microemulsions

ABSTRACTSelf-diffusion coefficients from pulsed-gradient spin-echo NMR are reported for four components of the tetradecylpyridinium bromide - 85% heptane/15% pentanol - water pseudoternary system. Measurements were taken throughout the inverted microemulsion region and also in a small isotropic region beyond the domain of lamellar liquid crystals. Observations of the self-diffusion coefficients for water relative to those of the surfactant, oil and alchohol show several distinct structural transitions within the water-in-oil region of the phase diagram. The smaller isotropic region exhibits a complete inversion of phase relative to the water-in-oil region. Conductivity measurements were used to further clarify the NMR data. Subsequent small angle neutron scattering (SANS) measurements on the same system show the transition from the single particle (heavy water + Stern layer droplet) scattering regime at low water concentration to the mixed single/interdroplet scattering regime when the intermicellar distance becomes comparable to the size of the micelles.

THE ADMITTANCE OF A LINEAR ANTENNA IN A UNIAXIAL MEDIUM

The admittance of a thin, long linear antenna embedded in a uniaxial medium and inclined at an angle θ to the medium's axis is calculated by solving an integral equation. It is shown that the admittance is roughly the same as for an isotropic region with a suitably modified relative dielectric constant given by Keff = √[K(sin2θ K3 + cos2θ K)], where K and K3 are the components of the relative permittivity tensor. Some numerical results are presented.