Numerical simulation of heat transfer and hydrodynamics ring and V-shaped heat exchange intensifiers

© 2016, International Journal of Pharmacy and Technology. All rights reserved.An urgent task is the increase of thermal efficiency of pipes for heat exchangers. The greater efficiency of the pipes, the more compact heat exchangers can be created; its material consumption and cost will also reduce. The most common method is increasing the efficiency by applying surface heat exchange intensifiers. It is important to keep in mind that increasing the thermal efficiency by applying heat exchange intensifiers entails an increase of the hydraulic resistance of pipes. To create an effective intensifier we need to find the balance between the thermal efficiency growth and the hydraulic resistance growth. The results of numerical simulation of the process of heat transfer using a new kind of v-shaped intensifiers are presented in the work. A comparison of the thermal efficiency of v-shaped intensifiers with ring intensifiers and smooth pipes, and the comparison of the hydraulic resistance increase are given in the article. The research of hydrodynamic and heat exchange processes was carried out in turbulent regime within the range of Re numbers from 3000 to 40000 to assess the thermal-hydraulic efficiency of pipes in various flow regimes. The application of v-shaped intensifiers can improve thermal efficiency in the whole range of studies compared with ring intensifiers, at moderate growth of hydraulic resistance at low value of Re numbers

Entanglement Islands and Infrared Anomalies in Schwarzschild Black Hole

In this paper, island formation for entangling regions of finite size in the asymptotically flat eternal Schwarzschild black hole is considered. We check the complementarity property of entanglement entropy which was implicitly assumed in previous studies for semi-infinite regions. This check reveals the emergence of infrared anomalies after regularization of a Cauchy surface. A naive infrared regularization based on ``mirror symmetry'' is considered and its failure is shown. We introduce an improved regularization that gives a correct limit agreed with the semi-infinite results from previous studies. As the time evolution goes, the endpoints of a finite region compatible with the improved regularization become separated by a timelike interval. We call this phenomenon the ``Cauchy surface breaking''. Shortly before the Cauchy surface breaking, finite size configurations generate asymmetric entanglement islands in contrast to the semi-infinite case. Depending on the size of the finite regions, qualitatively new behaviour arises, such as discontinuous evolution of the entanglement entropy and the absence of island formation. Finally, we show that the island prescription does not help us to solve the information paradox for certain finite size regions.Comment: v1: 55 pages, 19 figures; v2: 57 pages, 19 figures, references added, Sec. 5 presentation improve

Time-Dependent Invariants for Dirac Equation and Newton-Wigner Position Operator

For Dirac equation, operator-invariants containing explicit time-dependence in parallel to known time-dependent invariants of nonrelativistic Schr\"odinger equation are introduced and discussed. As an example, a free Dirac particle is considered and new invariants are constructed for it. The integral of motion, which is initial Newton-Wigner position operator, is obtained explicitly for a free Dirac particle. For such particle with kick modeled by delta-function of time, the time-depending integral, which has physical meaning of initial momentum, is found.Comment: LATEX,21 pages,submitted to Physica Script

Nonlinearity Management in Higher Dimensions

In the present short communication, we revisit nonlinearity management of the time-periodic nonlinear Schrodinger equation and the related averaging procedure. We prove that the averaged nonlinear Schrodinger equation does not support the blow-up of solutions in higher dimensions, independently of the strength in the nonlinearity coefficient variance. This conclusion agrees with earlier works in the case of strong nonlinearity management but contradicts those in the case of weak nonlinearity management. The apparent discrepancy is explained by the divergence of the averaging procedure in the limit of weak nonlinearity management.Comment: 9 pages, 1 figure

New Occurrences of Anomalous Specimens of Anuran Amphibians in Northwest Upper Poochye

New data about anomalous amphibian specimens in northwest Upper Poochye are provided. We found anomalies like anophthalmia, dyscoria, corectopia and abnormal patterns

New Data on the Anomalies of Tailless Amphibians of the Volga Basin

This paper presents new findings on abnormal specimens of amphibians in the Volga basin. Some anomalies have been noted for the first time: macrophthalmia, eardrum anomalies in marsh frogs (P. ridibundus), the absence of a tympanic membrane in green toads and ectromelia in spadefoot Pallas samples (P. vespertinus)

Fast atomic transport without vibrational heating

We use the dynamical invariants associated with the Hamiltonian of an atom in a one dimensional moving trap to inverse engineer the trap motion and perform fast atomic transport without final vibrational heating. The atom is driven non-adiabatically through a shortcut to the result of adiabatic, slow trap motion. For harmonic potentials this only requires designing appropriate trap trajectories, whereas perfect transport in anharmonic traps may be achieved by applying an extra field to compensate the forces in the rest frame of the trap. The results can be extended to atom stopping or launching. The limitations due to geometrical constraints, energies and accelerations involved are analyzed, as well as the relation to previous approaches (based on classical trajectories or "fast-forward" and "bang-bang" methods) which can be integrated in the invariant-based framework.Comment: 10 pages, 5 figure