Intermittency Growth in Fluid Turbulence

Measurement and phenomenological analyses of intermittency growth in an experimental turbulent pipe flow and numerical turbulence are performed, for which working definitions such as degree, increment, and growth rate of intermittency are introduced with the help of quasiscaling theory. The logarithmic-normal inertial scaling model is extended to quasiscaling as the second-order truncation of the Taylor expansion and is used for studying the intermittency growth problem. The extended self-similarity properties are shown to be not consistent with the monotonicity of the third order local quasiscaling exponent and the nonmonotonic behaviour of the intermittency growth rate as a result of bottleneck. Digestions of the results with scale-dependent multifractals are provided.     

求解跨音速粘性流反问题的有限体积法

1前言叶轮机械气动热力学研究的最终目的之一，是为工程师提供可用以设计高性能、高效率叶轮机械的思想与方法。而在过去叶轮机械气动热力学的研究大都集中求解正问题上，即在给定几何形状的叶片的条件下来求解流场上的气动参数。因此，为了设计出高性能的叶型，通常是凭设计者的经验，通过试验或正问题流场的分析计算，对一系列几何形状相差不大的叶型进行筛选。用这种方法是非常耗时并导致昂贵的设计费用，而且这样也并不总能得到预期的效果。所以，正问题计算虽然在预测性能和筛选试验方案等方面具有重要价值，但对于叶栅设计，应该具有…     

Lattice Boltzmann Method for Diffusion-Reaction-Transport Processes in Heterogeneous Porous Media

Based on the lattice Boltzmann method and general theory of fluids flowing in porous media, a numerical model is presented for the diffusion-reaction-transport (DRT) processes in porous media. As a test, we simu]ate a DRT process in a two-dimensional horizontal heterogeneous porous medium. The influence of gravitation in this case can be neglected, and the DRT process can be described by a strongly heterogeneous diagnostic test strip or a thin confined piece of soil with stochastically distributing property in horizontal directions. The results obtained for the relations between reduced fluid saturation S, concentration c1, and concentration c2 are shown by using the visualization computing technique. The computational efficiency and stability of the model are satisfactory.     

非守恒型粘性流方程的展开方法和数值模拟

在曲线坐标系中，给出了非守恒粘性流矢量方程一种新的展开方法，应用此展开方法使方程的展开式得到简化。对扩压管和二维平面叶栅进行了数值计算，计算结果表明，所给出的新展开式具有实用价值。     

A Stationary Vortex Phenomenon above a Low-Aspect-Ratio Wing

A stationary vortex phenomenon above a nondelta low-aspect-ratio wing was obtained in three-dimensional unsteady numerical simulation.Flow visualization is conducted in water channel using hydrogen bubbles.The results verify that there is a vortex trapped above the low-aspect-ratio wing and the stationary vortex consisted of two semi-balls and anti-rotation vortices which are different from the leading edge vortices on the delta wing.     

Transportation Characteristics for a Class of Generalized N-Diffusion Equation with Convection

A suitable similarity transformation group is used to reduce the power law parabolic partial equation to a classof singular nonlinear boundary value problems. Analytical solutions and numerical solutions both are presented for the specific power law index N, conductivity and convective functions, and the associated transportation characteristics are discussed in detail.     

具有一般粘性和压力的可压缩Navier-Stokes方程组的真空状态

本文在压力和粘性系数是密度的一般函数的假设下, 研究了当初始密度间断地连接到真空时的一维粘性气体模型, 利用差分方法, 证明了可压缩Navier-Stokes方程组弱解的整体存在性和唯一性. 为了克服一般的粘性系数μ(ρ)代替通常的 ρ^θ给研究带来的困难, 本文得到了一些新的先验估计.