A New Lattice Bhatnagar-Gross-Krook Model for the Convection-Diffusion Equation with a Source Term

A new lattice Bhatnagar-Gross-Krook (LBGK) model for the convection-diffusion equation with a source term is proposed. Unlike the models proposed previously, the present model does not require any additional assumptionon the source term. Numerical results are found to be in excellent agreement with the analytical solutions. It is also found that the numerical accuracy of the model is much better than that of the existing models.     

对流占优扩散问题的经济型流线扩散有限元法

In this paper, the economical finite difference-streamline diffusion (EFDSD) schemes based on the linear F.E. space for time-dependent linear and non-linear convection-dominated diffusion problems are constructed. The stability and error estimation with quasi-optimal order approximation are established in the norm stronger than L^2 - norm for the schemes considered. It is indicated by the results obtained that,for linear F.E. space, the EFDSD schemes have the same specific properties of stability and convergence as the traditional FDSD schemes for the problems discussed.     

非定常的热传导-对流问题的非线性Galerkin混合元法(Ⅰ):时间连续情形

1．引言非线性Galerkin方法是一种求解带有耗散项的发展型偏微分方程的近似解的多重水平方法．该方法是将未知量分裂成两项域多项），它们分别属于不同网格尺度的离散空间，在计算过程中，对于“小尺度”的分量引人简化逼近，使该方法变得很便利．这些方法原先主要是在Fourier普离散化时提出的（参见Foias－－Mauleyffemam［1］，Maxion－－Temam［2］，FOias－－Jolly－Kevrelddis－－Titi［3］，Devulder－－Marinn－－Titi［4］以及当中的文献）．关于非线性Gajerldn方法的有限元逼近是Marinnffemam在［51中首先提出的．AitOnAll…     

几何位置对封闭方腔内水平孤立平板自然对流换热的影响

本文以冰箱蒸发器等实际问题为背景，以空气为介质用数值模拟方法研究了封闭方腔内水平孤立平板层流自然对流时Ｒａ数及平板位置变化对Ｎｕｍ的影响，得出了可供工程应用参考的结论。同时用烟可视化的实验验证了计算结果的正确性。     

数值求解对流占优问题的分步解析方法

本文提出了数值求解对流占优问题的一种无条件L_∞稳定的分步解析方法。对于线性与非线性的对流占优问题,在数学上严格证明了分步解析方法的稳定性与收敛性,并给出了解的误差估计。     

高Pr数液体圆形自由射流局部恢复系数及换热特性的实验研究

1前言射流冲击对流换热具有非常高的换热系数山，按工质种类可分为气体射流和液体射流。射流冲击特别是以液体为工质的射流具有极高的换热率山。在实际应用中，空气射流一般都具有较高的流速。在射流速度极高，不能忽略粘性耗散的情况下，要用壁面温度见与射流的绝热壁温Ta。之差来定义对流换热系数h：h二q八Tw一见。）（1）式中绝热壁温定义为Taw一Ti＋，。‘／（iC）（z）其中，为恢复系数，。为射流出口流速，or为定压比热，Ti为射流静温。对于射流冲击换热，上述公式最先在Gardon和Cobonpue关于高流速空气射流的文章问中报道，并为…     

Rayleigh-Marangoni-Benard instability in two-layer fluid system

Rayleigh-Marangoni-Bénard instability in a system of two-layer fluids is studied numerically. The convective instabilities in the system of Silicon Oil (10cSt) and Fluorinert (FC70) liquids have been analyzed. The critical parameters at onset of convection are presented in a large range of two-layer depth ratios from 0.2 to 5.0. Numerical results show that the instability of the two-layer system depends strongly on its depth ratio. When the depth ratio increases, the instability mode changes from mechanical coupling to thermal coupling. Between these two typical coupling modes, a time-dependent oscillation is detected. Nevertheless, traveling wave states are found in the case of oscillatory instability. The oscillation mode results from the competition between Rayleigh instability and Marangoni effect. The project supported by the National Natural Science Foundation of China (10372105) and the Knowledge Innovation Program of Chinese Academy of Sciences (KJCX2-SW-L05)     

对流扩散方程的三层WENO-MMOCAA差分方法

本文把三层修正特征线法,MMOCAA 差分方法及WENO 插值相结合,提出了求解对流扩散方程的三层WENO-MMOCAA 差分格式.此格式关于时间具有二阶精度,关于空间具有二阶以上精度且可避免基于二次以上Lagrange 插值的三层MMOCAA 差分方法在解的大梯度附近所产生的振荡.本文使用新的分析方法,给出了格式的误差估计.本文的数值算例表明新格式可消除振荡.     

对流湍流池Fried相干长度的光学结构

利用不同的方法，测量并比较了用自适应光学补偿实验的对流湍流池的相干长度，给出到达角起伏谱和起伏方差的概率分布，结果表明，在对流湍流池中，光束的到达角起伏谱满足“－８／３”幂，由于相位起伏服从正态分布，因此到达角起伏的方差呈Ｘ＾２分布，到达角起伏在水平和垂直方向上的谱完全一致表明了湍流池湍流的各向同性特征，相干长度与对流湍流池上下温差的实验结果，符合以往对流湍流池的流体力学和热力学相心关系。