Numerical modeling of the thermal discharge of the Laguna Verde power station

El presente trabajo contribuye al conocimiento del comportamiento de las descargas térmicas en aguas marinas costeras mediante la implementación y la aplicación de un modelo numérico que resuelve las ecuaciones de Navier-Stokes-Reynolds para aguas someras y la ecuación de la energía para la temperatura. El modelo numérico toma en cuenta el flujo de calor en la capa superficial, donde interactúan la superficie libre del mar y la atmósfera. Como caso de estudio, se analiza la dispersión de la pluma térmica de la Central Nucleoeléctrica Laguna Verde (CNLV), ubicada en el Estado de Veracruz, México. Las simulaciones numéricas se llevan a cabo teniendo en cuenta la información ambiental, que incluye información batimétrica, oceanográfica, meteorológica e hidrológica, y las condiciones de operación de la descarga de la CNLV. Con base en comparaciones con datos medidos en campo y en el criterio de eficiencia de Nash-Suffle para verificar la calidad de la solución numérica, se considera que los resultados obtenidos son bastante satisfactorios.This work contributes to the study of nuclear plant thermal discharges in coastal areas by using a numerical model which solves the Navier-Stokes-Reynolds equations for shallow waters and the energy equation for computing temperature variations. The numerical model takes into account the heat flux given in the upper layer, where the free surface and the atmosphere interact. In this study, the thermal plume dispersion from the nuclear power plant Laguna Verde, Veracruz, Mexico, is analyzed. Bathymetry, oceanographic, meteorological, hydrologic and plant operating data are used to run numerical simulations. The results are compared against observed data showing good agreement. The Nash-Suffles criterion is also applied to verify the quality of the numerical solution obtaining suitable results.Peer Reviewe

A systematic correlation between two-dimensional flow topology and the abstract statistics of turbulence

Velocity differences in the direct enstrophy cascade of two-dimensional turbulence are correlated with the underlying flow topology. The statistics of the transverse and longitudinal velocity differences are found to be governed by different structures. The wings of the transverse distribution are dominated by strong vortex centers, whereas, the tails of the longitudinal differences are dominated by saddles. Viewed in the framework of earlier theoretical work this result suggests that the transfer of enstrophy to smaller scales is accomplished in regions of the flow dominated by saddles.Comment: 4 pages, 4 figure

A classical explanation of quantization

In the context of our recently developed emergent quantum mechanics, and, in particular, based on an assumed sub-quantum thermodynamics, the necessity of energy quantization as originally postulated by Max Planck is explained by means of purely classical physics. Moreover, under the same premises, also the energy spectrum of the quantum mechanical harmonic oscillator is derived. Essentially, Planck's constant h is shown to be indicative of a particle's "zitterbewegung" and thus of a fundamental angular momentum. The latter is identified with quantum mechanical spin, a residue of which is thus present even in the non-relativistic Schroedinger theory.Comment: 20 pages; version accepted for publication in Foundations of Physic

Measurement of the 58Ni(α, γ) 62Zn reaction and its astrophysical impact

Funding Details: PHY 08-22648, NSF, National Science Foundation; PHY 0969058, NSF, National Science Foundation; PHY 1102511, NSF, National Science FoundationCross section measurements of the 58Ni(α,γ)62Zn reaction were performed in the energy range Eα=5.5to9.5 MeV at the Nuclear Science Laboratory of the University of Notre Dame, using the NSCL Summing NaI(Tl) detector and the γ-summing technique. The measurements are compared to predictions in the statistical Hauser-Feshbach model of nuclear reactions using the SMARAGD code. It is found that the energy dependence of the cross section is reproduced well but the absolute value is overestimated by the prediction. This can be remedied by rescaling the α width by a factor of 0.45. Stellar reactivities were calculated with the rescaled α width and their impact on nucleosynthesis in type Ia supernovae has been studied. It is found that the resulting abundances change by up to 5% when using the new reactivities. © 2014 American Physical Society.Peer reviewe

Hysteresis at low Reynolds number: the onset of 2D vortex shedding

Hysteresis has been observed in a study of the transition between laminar flow and vortex shedding in a quasi-two dimensional system. The system is a vertical, rapidly flowing soap film which is penetrated by a rod oriented perpendicular to the film plane. Our experiments show that the transition from laminar flow to a periodic K\'arm\'an vortex street can be hysteretic, i.e. vortices can survive at velocities lower than the velocity needed to generate them.Comment: RevTeX file 4 pages + 5 (encapsulated postscript) figures. to appear in Phys.Rev.E, Rapid Communicatio

Electroconvection in a Suspended Fluid Film: A Linear Stability Analysis

A suspended fluid film with two free surfaces convects when a sufficiently large voltage is applied across it. We present a linear stability analysis for this system. The forces driving convection are due to the interaction of the applied electric field with space charge which develops near the free surfaces. Our analysis is similar to that for the two-dimensional B\'enard problem, but with important differences due to coupling between the charge distribution and the field. We find the neutral stability boundary of a dimensionless control parameter ${\cal R}$ as a function of the dimensionless wave number ${\kappa}$. ${\cal R}$, which is proportional to the square of the applied voltage, is analogous to the Rayleigh number. The critical values ${{\cal R}_c}$ and ${\kappa_c}$ are found from the minimum of the stability boundary, and its curvature at the minimum gives the correlation length ${\xi_0}$. The characteristic time scale ${\tau_0}$, which depends on a second dimensionless parameter ${\cal P}$, analogous to the Prandtl number, is determined from the linear growth rate near onset. ${\xi_0}$ and ${\tau_0}$ are coefficients in the Ginzburg-Landau amplitude equation which describes the flow pattern near onset in this system. We compare our results to recent experiments.Comment: 36 pages, 7 included eps figures, submitted to Phys Rev E. For more info, see http://mobydick.physics.utoronto.ca

Zwitters: particles between quantum and classical

We describe both quantum particles and classical particles in terms of a classical statistical ensemble, characterized by a probability distribution in phase space. By use of a wave function in phase space both can be treated in the same quantum formalism. The different dynamics of quantum and classical particles resides then only from different evolution equations for the probability distribution. Quantum particles are characterized by a specific choice of observables and time evolution of the probability density. All relations for a quantum particle in a potential, including interference and tunneling, can be described in terms of the classical probability distribution. We formulate the concept of zwitters - particles for which the time evolution interpolates between quantum and classical particles. Experiments can test a small parameter which quantifies possible deviations from quantum mechanics.Comment: extended discussion of possible realizations of zwitters, including macroscopic droplets or BEC condensate

A new experiment for the determination of the 18F(p,alpha) reaction rate at nova temperatures

The 18F(p,alpha) reaction was recognized as one of the most important for gamma ray astronomy in novae as it governs the early 511 keV emission. However, its rate remains largely uncertain at nova temperatures. A direct measurement of the cross section over the full range of nova energies is impossible because of its vanishing value at low energy and of the short 18F lifetime. Therefore, in order to better constrain this reaction rate, we have performed an indirect experiment taking advantage of the availability of a high purity and intense radioactive 18F beam at the Louvain La Neuve RIB facility. We present here the first results of the data analysis and discuss the consequences.Comment: Contribution to the Classical Novae Explosions conference, Sitges, Spain, 20-24 May 2002, 5 pages, 3 figure

Constraining the S factor of 15N(p,g)16O at Astrophysical Energies

The 15N(p,g)16O reaction represents a break out reaction linking the first and second cycle of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen range. The reaction is dominated by two broad resonances at Ep = 338 keV and 1028 keV and a Direct Capture contribution to the ground state of 16O. Interference effects between these contributions in both the low energy region (Ep < 338 keV) and in between the two resonances (338 <Ep < 1028 keV) can dramatically effect the extrapolation to energies of astrophysical interest. To facilitate a reliable extrapolation the 15N(p,g)16O reaction has been remeasured covering the energy range from Ep=1800 keV down to 130 keV. The results have been analyzed in the framework of a multi-level R-matrix theory and a S(0) value of 39.6 keV b has been found.Comment: 15 pages, 9 figure