排序方式: 共有76条查询结果,搜索用时 15 毫秒
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Particle fluctuation and gas turbulence in dense gas-particle flows are less studied due to complexity of the phenomena. In the present study, simulations of gas turbulent flows passing over a single particle are carried out first by using RANS modeling with a Reynolds stress equation turbulence model and sufficiently fine grids, and then by using LES. The turbulence enhancement by the particle wake effect is studied under various particle sizes and relative gas velocities, and the turbulence enhancement is found proportional to the particle diameter and the square of velocity. Based on the above results, a turbulence enhancement model for the particle-wake effect is proposed and is incorporated as a sub-model into a comprehensive two-phase flow model, which is then used to simulate dilute gas-particle flows in a horizontal channel. The simulation results show that the predicted gas turbulence by using the present model accounting for the particle wake effect is obviously in better agreement with the experimental results than the prediction given by the model not accounting for the wake effect. Finally, the proposed model is incorporated into another two-phase flow model to simulate dense gasparticle flows in a downer. The results show that the particle wake effect not only enhances the gas turbulence, but also amplifies the particle fluctuation. 相似文献
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双曲型守恒律的一种高精度TVD差分格式 总被引:3,自引:0,他引:3
构造了一维双曲型守恒律方程的一个高精度高分辨率的守恒型TVD差分格式.其主要思想是:首先将计算区域划分为互不重叠的小单元,且每个小单元再根据希望的精度阶数分为细小单元;其次,根据流动方向将通量分裂为正、负通量,并通过小单元上的高阶插值逼近得到了细小单元边界上的正、负数值通量,为避免由高阶插值产生的数值振荡,进一步根据流向对其进行TVD校正;再利用高阶Runge KuttaTVD离散方法对时间进行离散,得到了高阶全离散方法.进一步推广到一维方程组情形.最后对一维欧拉方程组计算了几个算例. 相似文献
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宋福民 《应用泛函分析学报》2005,7(1):13-21
旨在Banach空间中研究微分包含的周期边值问题(PBVP).假设F(t,u)仅满足弱Carathèodory条件,并不使用紧性条件,然而仍证明了该PBVP的唯一解能通过迭代序列的一致极限得到,并且还给出了解的误差估计. 相似文献
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浮雕全息图的转印复制技术研究 总被引:2,自引:0,他引:2
采用光学树脂作为转印介质复制浮雕全息图,适于将全息图复制到硬质基底材料上.对光敏型及热敏型两种树脂用于复制浮雕全息图进行了试验,实验结果表明:复制品的衍射效率、空间频率均接近原版全息图,并具有良好的环境稳定性.运用独特的一次转移复制工艺,工艺流程简单、设备投资少,在批量化复制生产中具有实用价值. 相似文献
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Automatic recognition and evaluation of micro-contaminant particles on ultra-smooth optical substrates using image analysis method 总被引:3,自引:0,他引:3
X. K. Shi M. Hua E. H. M. Cheung M. Li W. Z. Yuan 《Optics and Lasers in Engineering》2004,41(6):901-917
Micro-contaminant particles on surface of optical substrate have unfavorable influence on light characteristics and instability of optical devices. Proper recognition and evaluation of micro-contaminant particles on post-cleaning substrate are important in fabricating high-performance optical substrates. Based on image analysis and difference of gray scale threshold in image zones, this paper presents a technique for automatically recognizing micro-contamination, and the relevant software developed for on-line evaluation of the level of cleanliness on ultra-smooth optical substrate. Using the self-developed software incorporating high-resolution microscope, optical yttrium iron garnet (YIG) and K8 substrate surfaces of post-chemical mechanical polishing (CMP) were investigated. Results from analyzing the YIG and K8 optical substrates before-and-after laser cleaning illustrated the success of the developed automatic recognition and on-line evaluation system in identifying the micro-contaminant particles on the ultra-smooth substrate surface. 相似文献
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