共查询到20条相似文献,搜索用时 15 毫秒
1.
We study the kinetic behavior of a two-species aggregation-migration model in which an irreversible aggregation
occurs between any two clusters of the same species and a reversible migration occurs simultaneously between two different species. For a simple model with constant aggregation rates and
with the migration rates
KA(i;j)=K'A(i;j) ∝ijv1 and
KB(i;j)=K'B(i;j) ∝ijv2, we find that the evolution behavior of the system depends crucially on the
values of the indexes v1 and v2. The aggregate size
distribution of either species obeys a conventional scaling law for most cases. Moreover, we also generalize the two-species system to the multi-species case and analyze its kinetic behavior
under the symmetrical conditions. 相似文献
2.
射频辉光放电CH4等离子体一维流体动力学模拟 总被引:1,自引:1,他引:0
完整建立一个关于射频辉光放电CH4等离子体的流体动力学模型.模型包括基于迁移-扩散近似的粒子平衡方程、电子能量平衡方程,共包含了20种粒子(环境气体粒子,激发态粒子,离子和电子)和49类化学反应(电子-中性环境粒子、离子-中性环境粒子、激发态粒子-激发态粒子(中性环境粒子)).结果表明,在强电场区域有较高的电子反应率系数;等离子体中除源气体CH4外,H2,C2H6,C3H8,C2H4和C2H2也有较高的密度含量;激发态粒子中,CH3含量最高,密度约为1019m-3;在较低放电压力时(如18 Pa),CH5+在离子成分中密度含量最高,当放电压力较高时(如67Pa),C2H5+在离子成分中占主导地位;除C2H5+外,其它各离子和激发态粒子在极板上的粒子流量随功率的增大逐渐升高. 相似文献
3.
在统计力学理论基础上,本文提出了一个考虑氢键对自扩散系数影响的方程.这个方程为非氢键贡献部分与氢键贡献部分之积,其中自扩散系数的非氢键部分由Lennard-Jones链模型求得,而一个分子中的平均氢键数随温度和密度的变化关系使用统计缔合流体理论得到。链节之间的相互作用能量参数由粘度的关联式获得,其它四个参数则由扩散系数的实验数据获得。对7个典型的缔合流体在相当宽的温度压力范围内计算的平均相对百分误差为5.98%。 相似文献
4.
多相非牛顿流体驱替过程的格子Boltzmann模拟 总被引:1,自引:0,他引:1
将非牛顿流体模型引入多相格子Boltzmann方法(LBM),研究多相非牛顿流体的驱替过程.首先以牛顿流体驱替过程作对照,比较非牛顿流体的驱替特性.然后基于简单结构模型,分析不同界面张力下,非牛顿流体的驱替能力和驱替过程中被驱替相的形态变化规律,揭示界面张力的影响机理.结果表明:界面张力在驱替过程中起阻碍作用,其它参数相同情况下,界面张力越低,流体的驱替能力越强.最后,结合四参数随机生长(QSGS)结构生成方法,模拟不同压差、不同界面张力以及不同润湿性条件下多孔复杂结构内的非牛顿多相驱替过程,分析这些参数对过程的影响. 相似文献
5.
等效折射率模型研究光子晶体光纤的色散特性 总被引:16,自引:4,他引:16
应用等效折射率模型对折射率导模光子晶体光纤的群速度色散特性进行了详细的讨论。由于光子晶体光纤由单一材料(SiO2)制成,光纤的波导色散决定了总色散,因此讨论中将群速度色散分解为波导色散和材料色散,研究了波导色散与光子晶体光纤的结构参量孔距∧、相对孔径f的关系。分析表明,在f一定的情况下,光子晶体光纤的波导色散与孔距∧的关系符合麦克斯韦方程的比例性质;而在孔距∧确定的情况下,光子晶体光纤的波导色散的零点、极小值点位置与f在所讨论的波长范围内存在线性关系。最后举例说明了通过调整光子晶体光纤的结构参量,可以灵活地设计其色散特性。 相似文献
6.
S. W. Lovesey 《Journal of statistical physics》1978,19(4):367-390
The renormalization group method proposed by 't Hooft is developed for the study of scaling properties of some models of nonequilibrium phenomena. For one of two models studied in detail, the Langevin equation for the random variables contains a bilinear streaming velocity and the stationary probability distribution is Gaussian. The time-dependent Ginzburg-Landau model is chosen as a second example because it illustrates the advantage of the 't Hooft method of not having to specify a particular renormalization point. The scaling exponents for a model of the liquid-gas phase transition are calculated in lowest order to illustrate application of the method to a multifield system. 相似文献
7.
CHENG Yan HU Cui-E ZENG Zhao-Yi GONG Min GOU Qing-Quan 《理论物理通讯》2009,51(5):904-908
The phonon and thermodynamics properties of face-centered cubic CaF2 at high pressure and high temperature are investigated by using the shell model interatomic pair potential within General Utility Lattice Program (GULP). The phonon dispersion curves and the corresponding density of state (PDOS) in this work are consistent with the experimental data and other theoretical results. The transverse optical (TO) and longitudinal optical (LO) mode splitting as well as heat capacity at constant volume Cv and entropy S versus pressure and temperature are also obtained. 相似文献
8.
Scaling theory of transient phenomena near the instability point 总被引:1,自引:0,他引:1
Masuo Suzuki 《Journal of statistical physics》1977,16(1):11-32
A general scaling theory of transient phenomena is formulated near the instability point for the moments of the relevant intensive macrovariable, for the generating function, and for the probability distribution function. This scaling theory is based on a generalized scale transformation of time. The whole range of time is divided into three regions, namely the initial, scaling, and final regions. The connection procedure between the initial region and the scaling region is studied in detail. This scaling treatment has overcome the difficulty of divergence of the variance for a large time which was encountered in the -expansion, and this scaling theory yields correct values of moments to order unity for an infinite time. Some instructive examples are discussed for the purpose of clarifying the concepts of the scaling theory. 相似文献
9.
10.
A transverse Ising spin system, in the presence of time-dependentlongitudinal field, is studied by the effective-field theory (EFT). Theeffective-field equations of motion of the average magnetization are givenfor the simple cubic lattice (Z = 6) and the honeycomb lattice (Z = 3).The Liapunov exponent λ is calculated for discussing the stability of the magnetization and it is used to determine the phase boundary. Thedynamic phase transition diagrams in h0/ ZJ -Γ/ZJ plane and in h0/ZJ-T/ZJ plane have been drawn, and there is no dynamical tricritical point on the dynamic phase transition boundary. The effect of the thermal fluctuations upon the dynamic phase boundary has been discussed. 相似文献
11.
基于广义外势中的非广延统计理论,运用理论解析与数值模拟方法,研究磁场中非广延极端相对论费米气体的热力学性质,给出总能、热容量、化学势的解析式,分析非广延参数、极端相对论效应、磁场及温度对系统热力学性质的影响机理.研究显示,非广延参数不仅对热力学性质有直接的影响,而且也影响着磁场的物理效应. 随温度的升高,非广延参数及磁场对热力学性质的影响均被放大.极端相对论效应对化学势及热容量有特别显著的影响. 相似文献
12.
In this paper, the Clarkson–Kruskal direct approach is employed to investigate the exact solutions of the2-dimensional rotational Euler equations for the incompressible fluid. The application of the method leads to a system of completely solvable ordinary differential equations. Several special cases are discussed and novel nonlinear exact solutions with respect to variables x and y are obtained. It is of interest to notice that the pressure p is obtained by the second kind of curvilinear integral and the coefficients of the nonlinear solutions are solitary wave type functions like tanh(kt/2)and sech(kt/2) due to the rotational parameter k = 0. Such phenomenon never appear in the classical Euler equations wherein the Coriolis force arising from the gravity and Earth's rotation is ignored. Finally, illustrative numerical figures are attached to show the behaviors that the exact solutions may exhibit. 相似文献
13.
This paper investigates the three-dimensional flow of a Sisko fluid over a bidirectional stretching sheet, in a porous medium. By using the effect of Cattaneo-Christov heat flux model, heat transfer analysis is illustrated. Using similarity transformation the governing partial differential equations are transferred into a system of ordinary differential equations that are solved numerically by applying Nachtsheim-Swigert shooting iteration technique along with the 6-th order Runge-Kutta integration scheme. The effect of various physical parameters such as Sisko fluid, ratio parameter, thermal conductivity, porous medium, radiation parameter, Brownian motion, thermophoresis, Prandtl number, and Lewis number are graphically represented. 相似文献
14.
W. Korneta 《Czechoslovak Journal of Physics》2002,52(2):313-316
The topological and geometrical properties of Voronoi cells generated for 2D fluid of hard disks with Ising-like spins near the second-order phase transition from the paramagnetic to ferromagnetic phase are described for different disk densities. The comparison with Voronoi cells generated for the random hard disk system is given. 相似文献
15.
16.
17.
We consider the problem of determining analytically some exact solutions of the concentration u(x, y, t) of particles moving by diffusion and advection or drift. It is assumed that the advection is nonlinear. The driven diffusive flow is impeded by an impenetrable obstacle (rod) of length L. The exact solutions for u are evaluated for small and big values of vL/D, where v is the drift velocity and D is the diffusion coefficient. The results show that in some regions in the (x, y) plane the concentration first increases (or decreases) monotonically and then is nearly constant after some critical length L. The location at which u is nearly constant depends on the nature of the driving field v/D. This problem has relevance for the size segregation of particulate matter which results from the relative motion of different-size particles induced by shaking. Methods of symmetry reduction are used in solving the nonlinear advection-diffusion equation in (2+1) dimensions. 相似文献
18.
为研究表面界面粗化生长中孔洞的标度行为,在对Ballistic Deposition(BD)模型进行数值模拟的基础上,对模型中孔洞的模拟生长情况进行统计和分析.结果表明,BD模型中孔洞数目随模型生长时间的变化从初始阶段的高于线性而渐趋近于线性,并对该规律进行理论分析. 相似文献
19.
The cusped field thruster is a kind of newly developed electric propulsion device. The electric field at the channel exit and the low frequency oscillation were measured by former experiments. While the formation mechanism of them have not been fully interpreted yet. Through studying two distinguishing typical electron paths in the thrusters, a fluid model is built up along two electron paths, and then the model is completed by synthetically analyzing the effect of two electron paths. Time‐averaged electric potential distribution, anode current oscillation curve and time‐synchronized atom density and ion density distribution are obtained by simulation. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
The general gradient theory of fluid microstructures is outlined. This theory reduces the determination of fluid microstructures to a boundary value problem. The density and pressure tensor profiles and the tension of planar thin films and layered structures in one-component fluids are investigated. The boundary conditions determining these structures are given a geometric interpretation in the free energy-density diagram. Discussed are the implications of the theory for the validity of Antonov's rule, the duplex film hypothesis, and the asymptotic theory of disjoining pressure and of the origin of a characteristic length scale in spinodal decomposition.This work was supported financially by the U.S. Department of Energy and the National Science Foundation. 相似文献