基于真实气体效应的湍流标度律特性

在量热完全气体、热完全气体和化学反应完全气体等3种气体模型假设下,利用Mach数为4.05、壁温为1 300 K的超声速槽道湍流的直接数值模拟（direct numerical simulation,DNS）结果,对标度律和自相似性做了详细分析.结果表明,不仅在量热完全气体模型下存在标度律和扩展自相似性,而且在热完全气体和化学反应完全气体模型下标度律和扩展自相似性仍然成立.压缩性的影响使得速度结构函数通过Favre平均获得更为合适.与热完全气体模型的结果相比,化学反应完全气体和量热完全气体模型的结果吻合更好.      

Relative Scaling Exponents and Intermittency in Compressible Turbulent Channel Flows

The relative scaling exponents and intermittency of three-dimensional compressible turbulent channel flow are investigated by using direct numerical simulation. One case is subsonic flow （Mα=0.8）, the other is supersonic （Mα=1.3）, and the Reynolds numbers based on the mean bulk velocity and channel half-width are 2826 and 3010, respectively. The analysis of the local slopes of sixth order velocity structure function to third order reveals that there is a well-defined scaling range for 10〈y^＋〈100. it is also noted that the intermittency of longitudinal velocity increments in this region is stronger than that of the transverse ones. Comparison with the incompressible case shows that the location of the most intensive intermittency moves toward the log-law region, which is related to the displacement of streamwise vortical structures in the near-wall region.     

掺杂的标度性

所谓掺杂的标度性指的是：分子晶体，如ＮＨ４ＮＯ３晶体在其相变过程中，其所掺杂的离子如Ｎａ＋，Ｋ＋，Ａｇ＋，Ｐｂ２＋或Ｆ－，Ｃｌ－，Ｂｒ－等，会对相变有影响。影响的强度表现在掺杂离子间的间距ｄ对其质量的根号Ｍ的标度，即ｄ／Ｍ这个参数上。这意味着对不同的...     

Scaling Properties of Runaway Electrons in HL-1M Tokamak

1 Introduction Runaway electrons in tokamaks have been widely studied theoretically and experimentally. Runaway electrons have received lately a great attention due to several reasons： a） the possibility to study electromagnetic turbulence by measuring the runaway flux fluctuations and its energy spectra, and b） the runaway electrons are powerful diagnostics capable of yielding valuable information on the actual distribution function of fusion experiments.     

Scaling Properties of Runaway Electrons

Runaway electrons in tokamaks have been widely studied theoretically and experimentally. The runaway confinement time τ1 in ohmic and additionally heated tokamak plasmas presents an anomalous behavior when compared with theoretical predictions based on neoclassical models. Runaway electrons have received lately a great attention due to several reasons： （a） the possibility to study electromagnetic turbulence by measuring the runaway flux fluctuations and its energy spectra, and （ b ） the runaway electrons are powerful diagnostics capable of yielding valuable information on the actual distribution function of fusion experiments.     

Three-Mode Entangled State Representation of Continuum Variables and Optical Four-Wave Mixing

We establish a new three-mode entangled state representation , of continuum variables, which make up a complete set. Using optical four-wave mixing and a beam splitter transform we can prepare , . Based on , a new number-difference--operational-phase uncertainty relation is established and the corresponding squeezing dynamics is discussed.     

New Formulation of Weyl Quantization Scheme in Coherent State Representation

By virtue of the technique of integration within an ordered product of operators we present a new formulation of the Weyl quantization scheme in the coherent state representation, which not only brings convenience for calculating the Weyl correspondence of normally ordered operators, but also directly leads us to find both the coherent state representation and the Weyl ordering representation of the Wigner operator.     

Scaling,Renormalization and Statistical Conservation Laws in the Kraichnan Model of Turbulent Advection

We present a systematic way to compute the scaling exponents of the structure functions of the Kraichnan model of turbulent advection in a series of powers of ξ, adimensional coupling constant measuring the degree of roughness of the advecting velocity field. We also investigate the relation between standard and renormalization group improved perturbation theory. The aim is to shed light on the relation between renormalization group methods and the statistical conservation laws of the Kraichnan model, also known as zero modes.     

高温空气燃烧炉内湍流混合特性的数值研究

应用自行研发的三维流动、燃烧、传热和污染物NO_x湍流生成的数值模拟程序,对高温空气燃烧实验模型炉进行了湍流扩散燃烧混合特性的数值模拟.数值预报了燃烧室内气体燃料和空气的混合物分数及其湍流脉动的三维分布.数值研究结果表明:在一定的几何条件和气体动力学条件下,高温空气燃烧的湍流混合在更广泛的区域内以较小梯度的进行;混合物分数的脉动主要分布在燃烧区,这表明高温空气燃烧的火焰厚度更大,具有燃烧释热更趋均匀的特性.数值模拟结果与相关的实验结果有相同的规律.     

Optical Four-Wave Mixing Operator, Fresnel Operators and Three-Mode Entangled State Representation

We analyse the optical four-wave mixing operator S and relate it to the two-mode Fresnel operator. It is shown that the direct product of the two-mode Fresnel operator and the single-mode Fresnel operator has a natural representation on the basis of a three-mode entangled state, which is constructed by S and a beam splitter transform.     

Diamond. Part 1

In this, the first of two articles on diamond, a review is given of its hardness, its sources, its fabrication and of many of its uses as a technological material. Some examples of etched diamond surfaces, growth features, surface polish and percussion marks are illustrated. The history of man-made diamonds is briefly reviewed.

In part 2, which will follow later, aspects to be treated will include absorption spectra, semi-conductivity, diamond counters and irradiation defects.     

Perturbed Arcs in Turbulent Axial Gas Flow II. Fluctuating Local Properties

As a continuation of the research described in Pt. I, local quantities are studied experimentally by electrostatic wall probing, time resolving shadowgraphy and radial luminosity profile scanning of arcs in turbulent axial gas flow. Turbulency of the gas coolant and thermal sheath properties are discussed as well as the consequencies of the gathered knowledge to theoretical modelling.     

Correct Path-Integral Formulation of Quantum Thermal Field Theory in Coherent State Representation

The path-integral quantization of thermal scalar, vector, and spinor fields is performed newly in the coherent-state representation. In doing this, we choose the thermal electrodynamics and φ⁴ theory as examples. By this quantization, correct expressions of the partition functions and the generating functionals for the quantum thermal electrodynamics and φ⁴ theory are obtained in the coherent-state representation. These expressions allow us to perform analytical calculations of the partition functions and generating functionals and therefore are useful in practical applications. Especially, the perturbative expansions of the generating functionals are derived specifically by virtue of the stationary-phase method. The generating functionals formulated in the position space are re-derived from the ones given in the coherent-state representation.     

Shock capturing with PDE-based artificial viscosity for DGFEM: Part I. Formulation

Artificial viscosity can be combined with a higher-order discontinuous Galerkin finite element discretization to resolve a shock layer within a single cell. However, when a non-smooth artificial viscosity model is employed with an otherwise higher-order approximation, element-to-element variations induce oscillations in state gradients and pollute the downstream flow. To alleviate these difficulties, this work proposes a higher-order, state-based artificial viscosity with an associated governing partial differential equation (PDE). In the governing PDE, a shock indicator acts as a forcing term while grid-based diffusion is added to smooth the resulting artificial viscosity. When applied to heat transfer prediction on unstructured meshes in hypersonic flows, the PDE-based artificial viscosity is less susceptible to errors introduced by grid edges oblique to captured shocks and boundary layers, thereby enabling accurate heat transfer predictions.     

Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation

By virtue of the squeezing-rotating entangled representation, we mainly establish the new two-mode phase operator and phase angle operat, or, which is a general form including the foregoing formalist in two-mode Fock space. In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotatlng coherent state, squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.     

Phase Properties of Two-Mode Squeezing-Rotating Entangled Representation

By virtue of the squeezing-rotating entangled representation, we mainly establish thc new two-mode phase operator and phase angle operator, which is a general form including the foregoing formalist in two-mode Fock space.In addition, the corresponding phase distribution function is given in the entangled representation. In terms of this definition, we also analyze the phase behavior of some simple two-mode states such as squeezing-rotating coherent state,squeezing-rotating vacuum state, and so on. It is found that the results exactly agree with the foregoing phase theory.