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12.
13.
Decaying homogeneous isotropic turbulence with an imposed mean scalar gradient is investigated numerically, thanks to a specific eddy-damped quasi-normal Markovian closure developed recently for passive scalar mixing in homogeneous anisotropic turbulence (BGC). The present modelling is compared successfully with recent direct numerical simulations and other models, for both very large and small Prandtl numbers. First, scalings for the cospectrum and scalar variance spectrum in the inertial range are recovered analytically and numerically. Then, at large Reynolds numbers, the decay and growth laws for the scalar variance and mixed velocity–scalar correlations, respectively, derived in BGC, are shown numerically to remain valid when the Prandtl number strongly departs from unity. Afterwards, the normalised correlation ρwθ is found to decrease in magnitude at a fixed Reynolds number when Pr either increases or decreases, in agreement with earlier predictions. Finally, the small scales return to isotropy of the scalar second-order moments is found to depend not only on the Reynolds number, but also on the Prandtl number. 相似文献
14.
We investigate finite lattice approximations to the Wilson renormalization group in models of unconstrained spins. We discuss first the properties of the renormalization group transformation (RGT) that control the accuracy of this type of approximation and explain different methods and techniques to practically identify them. We also discuss how to determine the anomalous dimension of the field. We apply our considerations to a linear sigma model in two dimensions in the domain of attraction of the Ising fixed point using a Bell–Wilson RGT. We are able to identify optimal RGTs which allow accurate computations of quantities such as critical exponents, fixed-point couplings and eigenvectors with modest statistics. We finally discuss the advantages and limitations of this type of approach. 相似文献
15.
The Yang–Mills system of field equations which includes coupling to an SU(2) scalar matter doublet is developed. It is shown that an SU(2) current for a scalar matter doublet can be developed. The basic structure which fits the Yang–Mills system is somewhat different from the case of the scalar triplet. Using this form for the scalar current, it is possible to write down the Yang–Mills system which couples to the scalar matter doublet. It is shown that several sets of solutions to this system of equations can be obtained. 相似文献
16.
认为物质的质量(能量)存在形式可分为两部分,一部分是以纯物质形式存在的,另一部分是以纯重力场形式存在的.物质质量(能量)这两种形式各自对应着相应的能量 动量张量,物质总的能量-动量张量可表示为Tμν=T(Ⅰ)μν+T(Ⅱ)μν,这里,T(Ⅰ)μν,T(Ⅱ)μν分别代表物质纯物质部分和纯重力场部分的能量-动量张量.通过类比电磁理论,定义:ωμ≡-c2gμ0/g00,并引入一个反对称张量Dμν=ωμ/xν-ων/xμ,则物质纯重力场部分的能量-动量张量为T(Ⅱ)μν=(DμρDρν-gμνDαβDαβ/4
关键词:
能量-动量张量
纯重力场
重力场方程
标量重力势
矢量重力势 相似文献
17.
Sergey Chervon 《General Relativity and Gravitation》2004,36(7):1547-1553
A new strategy of exact solutions construction in inflationary cosmology within the self-interacting scalar field theory is proposed. It is shown that inflationary models have no restrictions dictated by the slow-roll approximation on the self-interacting potential. The suggested approach makes it possible to compute precisely the e-folds numbers in inflationary scenarios. The scalar field with a logarithmic evolution in time is analyzed in details. Other possible types of scalar field evolution are discussed. 相似文献
18.
The Decay of Massive Scalar Field in Non-Static Gödel Type Universe with Viscous Fluid and Heat Flow
In this study, we have investigated the dynamics of non-static Gödel type rotating universe with massive scalar field, viscous fluid and heat flow in the presence of cosmological constant. For various cosmic matter forms, the behavior of the cosmological constant (Λ), shear (η) and bulk (ξ) viscosity coefficients and other kinematic quantities have studied in the early universe. We have showed the decay of massive scalar field in the non-static rotating Gödel type universe and we have obtained constant scalar field with and without source density. Also, we have investigated the effects of massive scalar field on the matter density and pressure. From solutions of the field equations, we have a cosmological model with non-zero expansion, shear, heat flux and rotation. Also some physical and geometrical aspects of the model discussed. 相似文献
19.
This paper discusses tunneling of scalar particles and
Dirac particles from the Taub-NUT-AdS black hole by the
Hamilton--Jacobi equation, initially used by Angheben et al,
and the Dirac equation, recently proposed by Kerner and Mann.
This is performed in the dragging coordinate frame so
as to avoid the ergosphere dragging effect. A general
form is obtained for the temperature of scalar and Dirac particles tunneling
from the Taub-NUT-Ads black hole, which is commensurate with other
methods as expected. 相似文献
20.
The nonlinear interactions between zonal flow and Rossby waves are studied by numerical simulations with focus on the effects of scalar nonlinearity. The numerical results show that the scalar nonlinearity has an appreciable influence on the Rossby dipole evolution and can reduce the threshold of the disturbance energy increase. 相似文献