A computational approach for investigating Coulomb interaction using Wigner–Poisson coupling

Entangled quantum particles, in which operating on one particle instantaneously influences the state of the entangled particle, are attractive options for carrying quantum information at the nanoscale. However, fully-describing entanglement in traditional time-dependent quantum transport simulation approaches requires significant computational effort, bordering on being prohibitive. Considering electrons, one approach to analyzing their entanglement is through modeling the Coulomb interaction via the Wigner formalism. In this work, we reduce the computational complexity of the time evolution of two interacting electrons by resorting to reasonable approximations. In particular, we replace the Wigner potential of the electron–electron interaction by a local electrostatic field, which is introduced through the spectral decomposition of the potential. It is demonstrated that for some particular configurations of an electron–electron system, the introduced approximations are feasible. Purity, identified as the maximal coherence for a quantum state, is also analyzed and its corresponding analysis demonstrates that the entanglement due to the Coulomb interaction is well accounted for by the introduced local approximation.

Fluid-Structure Interaction Response of a Water Conveyance System with a Surge Chamber during Water Hammer

Fluid–structure interaction (FSI) is a frequent and unstable inherent phenomenon in water conveyance systems. Especially in a system with a surge chamber, valve closing and the subsequent water level oscillation in the surge chamber are the excitation source of the hydraulic transient process. Water-hammer-induced FSI has not been considered in preceding research, and the results without FSI justify further investigations. In this study, an FSI eight-equation model is presented to capture its influence. Both the elbow pipe and surge chamber are treated as boundary conditions, and solved using the finite volume method (FVM). After verifying the feasibility of using FVM to solve FSI, friction, Poisson, and junction couplings are discussed in detail to separately reveal the influence of a surge chamber, tow elbows, and a valve on FSI. Results indicated that the major mechanisms of coupling are junction coupling and Poisson coupling. The former occurs in the surge chamber and elbows. Meanwhile, a stronger pressure pulsation is produced at the valve, resulting in a more complex FSI response in the water conveyance system. Poisson coupling and junction coupling are the main factors contributing to a large amount of local transilience emerging on the dynamic pressure curves. Moreover, frictional coupling leads to the lower amplitudes of transilience. These results indicate that the transilience is induced by the water hammer–structure interaction and plays important roles in the orifice optimization in the surge chamber.

Williams-Wittrick Approach Application for an Effective Search for Natural Vibration Frequencies of Pipeline Systems With Fluid-Structure Interaction

The approach for quick and effective search of natural vibration frequencies of multibranched beam systems with distributed mass, developed by F.W. Williams and W.H. Wittrick, is adopted for complex pipe systems with fluid-structure interaction. The general principle of the matrix composition is formulated for the case of beam systems of arbitrary complexity. The flexibility of such principle allows to extend it and to take into account the fluid free vibration. The special approach is developed to consider the fluid boundary conditions at the ends of the pipeline and a volumetric balance equation in the junctions. The formulated methods are implemented in an effective calculation procedure for the search of natural frequencies of coupled vibrations of the system with fluid-structure interaction, i.e. taking into account junction coupling as well as Poisson coupling. The procedure accuracy is demonstrated for a number of comparison examples.

Nonlinear Dynamic Modeling of Constant Force Supported Thermal Power Pipeline

In this paper, the Hamilton theory was applied to describe the dynamic model of Thermal Power Pipeline nonlinear fluid solid coupling vibration. The model includes the control equation of axial vibration and the transverse vibration of the pipeline, taking full account of the vibration characteristics of the fluid in the pipeline, effect of thermal deformation and constant support, as well as the friction coupling, Poisson coupling and junction coupling. The model is an attempt to the heating pipes and need to be further improved.

Dynamic Behavior of Complex Fluid-Filled Tubing Systems—Part 1: Tubing Analysis

A general transmission-matrix approach is given for finding the frequency response of linearized long-wavelength models for the vibration in systems with straight and curved fluid-filled tubes. Couplings between the fluid and wall motions include the Bourdon effect, frequency-dependent wall shear, the Poisson coupling and the effect of discontinuities. The introduction of a global transmission matrix allows nonplanar tubing systems of virtually any complexity to be analyzed, overcoming the round-off error problem that plagues the basic transmission-matrix approach for this and analogous system models. Corroborating experiments focus on the Poisson and Bourdon effects.