Similarity of the concentration field of gas-phase turbulent jets

This work is an experimental investigation of the turbulent concentration field formed when the nozzle gas from a round, momentum-driven, free turbulent jet mixes with gas entrained from a quiescent reservoir. The measurements, which were made with a non-intrusive laser-Rayleigh scattering diagnostic at Reynolds numbers of 5000, 16000, and 40000, cover the axial range from 20 to 90 jet exit diameters and resolve the full range of temporal and spatial concentration scales. Reynolds-number-independent and Reynolds-number-dependent similarities are investigated. The mean and r.m.s. values of the concentration are found to be consistent with jet similarity laws. Concentration fluctuation power spectra are found to be self-similar along rays emanating from the virtual origin of the jet. The probability density function for the concentration is also found to be self-similar along rays. Near the centreline of the jet, the scaled probability density function of jet fluid concentration is found to be nearly independent of the Reynolds number

On Mixing and Structure of the Concentration Field of Turbulent Jets

This work is an investigation of the mixing of the nozzle fluid of a round turbulent jet with the entrained reservoir fluid, using laser-Rayleigh scattering methods. Our measurements, at a Reynolds number of 5000, cover the axial range from 20 to 80 jet exit diameters and resolve the full range of temporal & spatial concentration scales. The measured mean & rms values of the concentration, and the mean scalar dissipation rate, when estimated from the time derivative of concentration, are consistent with jet similarity laws. Concentration fluctuation power spectra are found to be self-similar along rays emanating from the jet virtual origin. The probability density functions for the concentration, the time derivative of concentration, and the square of the time derivative of concentration, are compiled and are also self-similar along rays

The Extent Of Introgression Outside The Contact Zone Between Notropis Cornutus And Notropis Chrysocephalus (Teleostei: Cyprinidae)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137435/1/evo04362.pd

Simulations of atomic trajectories near a dielectric surface

We present a semiclassical model of an atom moving in the evanescent field of a microtoroidal resonator. Atoms falling through whispering-gallery modes can achieve strong, coherent coupling with the cavity at distances of approximately 100 nanometers from the surface; in this regime, surface-induced Casmir-Polder level shifts become significant for atomic motion and detection. Atomic transit events detected in recent experiments are analyzed with our simulation, which is extended to consider atom trapping in the evanescent field of a microtoroid.Comment: 29 pages, 10 figure

The time-reversal test for stochastic quantum dynamics

The calculation of quantum dynamics is currently a central issue in theoretical physics, with diverse applications ranging from ultra-cold atomic Bose-Einstein condensates (BEC) to condensed matter, biology, and even astrophysics. Here we demonstrate a conceptually simple method of determining the regime of validity of stochastic simulations of unitary quantum dynamics by employing a time-reversal test. We apply this test to a simulation of the evolution of a quantum anharmonic oscillator with up to $6.022\times10^{23}$ (Avogadro's number) of particles. This system is realisable as a Bose-Einstein condensate in an optical lattice, for which the time-reversal procedure could be implemented experimentally.Comment: revtex4, two figures, four page