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《Physics letters. [Part B]》1987,195(2):209-212
A two-dimensional SU(N) gauge model coupled to Weyl fermions is studied following recent suggestions for the quantization of potentially anomalous chiral theories. The Weyl fermion determinant is evaluated and the fermionic current is shown to be conserved due to the gauge invariance of the resulting quantum theory. As in the abelian case, the vector meson acquires a mass and the model is consistent provided a regularization parameter is conveniently chosen. 相似文献
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在开源的CFD 工具包OpenFOAM 环境下开发了基于低磁雷诺数的磁流体湍流数值模拟求解器,对 2π ×1×1的方管中无磁场湍流和磁流体湍流进行直接数值模拟研究,给出了截面瞬时速度、平均速度的分布,截面对称中心线上的脉动速度的均方根值、湍动能的分布。计算结果表明,外加磁场对磁流体湍流具有抑制作用和并且这种抑制作用具有各向异性。 相似文献
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在开源的CFD工具包OpenFOAM环境下开发了基于低磁雷诺数的磁流体湍流数值模拟求解器,对2π×1×1的方管中无磁场湍流和磁流体湍流进行直接数值模拟研究,给出了截面瞬时速度、平均速度的分布,截面对称中心线上的脉动速度的均方根值、湍动能的分布。计算结果表明,外加磁场对磁流体湍流具有抑制作用和并且这种抑制作用具有各向异性。 相似文献
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This paper presents an adaptive moving mesh algorithm for two-dimensional (2D) ideal magnetohydrodynamics (MHD) that utilizes a staggered constrained transport technique to keep the magnetic field divergence-free. The algorithm consists of two independent parts: MHD evolution and mesh-redistribution. The first part is a high-resolution, divergence-free, shock-capturing scheme on a fixed quadrangular mesh, while the second part is an iterative procedure. In each iteration, mesh points are first redistributed, and then a conservative-interpolation formula is used to calculate the remapped cell-averages of the mass, momentum, and total energy on the resulting new mesh; the magnetic potential is remapped to the new mesh in a non-conservative way and is reconstructed to give a divergence-free magnetic field on the new mesh. Several numerical examples are given to demonstrate that the proposed method can achieve high numerical accuracy, track and resolve strong shock waves in ideal MHD problems, and preserve divergence-free property of the magnetic field. Numerical examples include the smooth Alfvén wave problem, 2D and 2.5D shock tube problems, two rotor problems, the stringent blast problem, and the cloud–shock interaction problem. 相似文献
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《中国物理 B》2021,30(9):94701-094701
We report a numerical study of the Prandtl-number(Pr) effects in two-dimensional turbulent Rayleigh-Benard convection.The simulations were conducted in a square box over the Pr range from 0.25 to 100 and over the Rayleigh number(Ra) range from 107 to 1010.We find that both the strength and the stability of the large-scale flow decrease with the increasing of Pr,and the flow pattern becomes plume-dominated at high Pr.The evolution in flow pattern is quantified by the Reynolds number(Re),with the Ra and the Pr scaling exponents varying from 0.54 to 0.67 and-0.87 to-0.93,respectively.It is further found that the non-dimensional heat flux at small Ra diverges strongly for different Pr,but their difference becomes marginal as Ra increases.For the thermal boundary layer,the spatially averaged thicknesses for all the Pr numbers can be described by δ_θ~Ra~(-0.30) approximately,but the local values vary a lot for different Pr,which become more uniform with Pr increasing. 相似文献
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Oliver Rudolph 《International Journal of Theoretical Physics》1996,35(8):1581-1636
In this work a generalization of the consistent histories approach to quantum mechanics is presented. We first critically
review the consistent histories approach to nonrelativistic quantum mechanics in a mathematically rigorous way and give some
general comments about it. We investigate to what extent the consistent histories scheme is compatible with the results of
the operational formulation of quantum mechanics. According to the operational approach, nonrelativistic quantum mechanics
is most generally formulated in terms of effects, states, and operations. We formulate a generalized consistent histories
theory using the concepts and the terminology which have proven useful in the operational formulation of quantum mechanics.
The logical rule of the logical interpretation of quantum mechanics is generalized to the present context. The algebraic structure
of the generalized theory is studied in detail. 相似文献
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We present measurements of the Nusselt number N as a function of the Rayleigh number R in cylindrical cells with aspect ratios 0. 5=gamma identical withD/d=12.8 ( D is the diameter and d is the height). We used acetone with a Prandtl number sigma = 4.0 for 10(5) less, similarR less, similar4x10(10). A fit of a power law N = N(0)R(gamma(eff)) over limited ranges of R yielded values of gamma(eff) from 0.275 near R = 10(7) to 0.300 near R = 10(10). The data are inconsistent with a single power law for N(R). For R>10(7) they are consistent with N = asigma-1/12R1/4+bsigma-1/7R3/7 as proposed by Grossmann and Lohse for sigma greater, similar2. 相似文献
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The control of transport due to electrostatic turbulence is investigated using test-particle simulations. We show that a barrier for the transport, that is, a region where transport is reduced, can be generated through the randomization of phases of the turbulent field. This corresponds to the annihilation of coherent structures which are present at all scales, without actually suppressing turbulence. When the barrier is active, a flux of particles towards the center of the simulation box is present inside the region where the barrier is located. 相似文献
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Vincent AP Yuen DA 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(3):2957-2963
We have conducted a high-resolution, two-dimensional direct numerical simulation of Rayleigh-Bénard convection with stress-free and periodic boundary conditions at a Rayleigh (Ra) number of 10(8) and Prandtl (Pr) number of unity. An aspect-ratio three box has been considered. A single cell has been used as the initial condition. First, the flow develops into time-dependent convection with a strong asymmetry and highly convoluted thermal plumes delineating a large-scale circulation. Smaller thermal plumes detach from the boundary layer and extend over the entire cell, creating a local inversion of the temperature gradient adjacent to the boundary layers. Then the conditions leading to the formation of internal waves are fulfilled, as the local Richardson number decreases sufficiently small to cross the linear threshold of Ri=0.25. Together with the strong shear, convective rolls with a Kelvin-Helmholtz wavelike character are produced. The secondary boundary layer itself becomes unstable and produces smaller plumes. At later times, the large-scale circulation is destroyed and the internal waves disappear. A Reynolds number, based on the global scale, of Re=500, is attained at this stage. Only isolated thermal plumes and vortices are present. Thus, internal waves can be generated at finite Prandtl number fluids for sufficiently high Ra in the presence of a large-scale circulation. Spectral analysis reveals that the kinetic energy decays with a logarithmic slope of -3, while the logarithmic slope of the thermal variance has a value of around -5 / 3. 相似文献
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Turbulent color fields, which can arise in the early and late stages of relativistic heavy ion collisions, may contribute significantly to the transport processes in the matter created in these collisions. We review the theory of these anomalous transport processes and discuss their possible phenomenology in the glasma and quasistationary expanding quark–gluon plasma. 相似文献
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We present measurements of the normalized charge transport or Nusselt number Nu as a function of the aspect ratio Gamma for turbulent convection in an electrically driven film. In analogy with turbulent Rayleigh-Bénard convection, we develop the relevant theoretical framework in which we discuss the local power-law scaling of Nu with a dimensionless electrical forcing parameter R. For these experiments where 10(4) less, similar R less, similar 2 x 10(5) we find that Nu approximately F(Gamma)Rgamma with either gamma=0.26 (+/-0.02) or gamma=0.20 (+/-0.03), in excellent agreement with the theoretical predictions of gamma=1/4 and 1/5. Our measurements of the aspect-ratio dependence of Nu for 0.3=Gamma=17 compares favorably with the function F(Gamma) from the scaling theory. 相似文献