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注水泥环空动态顶替界面长距离数值模拟 被引量:4
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作者 王涛 展转盈 燕迎飞 《非常规油气》 2018年第6期87-93,共7页
借助流体力学软件FLUENT对环空注水泥层流顶替进行了长距离的数值模拟。利用流体体积法(VOF)对两相顶替界面进行了界面重构。对顶替界面达到动态稳定形态的过程进行了描述,对不同偏心度、密度差、顶替速度和流体黏度条件下的顶替界面进... 借助流体力学软件FLUENT对环空注水泥层流顶替进行了长距离的数值模拟。利用流体体积法(VOF)对两相顶替界面进行了界面重构。对顶替界面达到动态稳定形态的过程进行了描述,对不同偏心度、密度差、顶替速度和流体黏度条件下的顶替界面进行了模拟。模拟结果显示,顶替开始后界面长度不断拉长,在正密度差下界面会达到动态稳定(在一个范围内波动)或者绝对稳定,并以此稳定界面向前推进,而动态稳定界面会使得窄间隙留下无法驱替的滞留层。在同心环空中,只要存在正密度差即可达到绝对稳定的界面;在偏心环空中高密度差下界面会达到绝对稳定,其他情况会获得动态稳定界面,此密度差节点与偏心度呈正相关;负密度差下界面均无法达到稳定;从对顶替界面达到稳定状态的影响效果来看,从大到小依次为偏心度、密度差、顶替速度和流体流变性能。该模拟结果对水泥浆密度设计、隔离液用量和环空注水泥施工有很好的指导性作用。 展开更多
关键词 层流 顶替界面 动态稳定 数值模拟 长距离环空
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Spacelike Graphs with Parallel Mean Curvature in Pseudo-Riemannian Product Manifolds 被引量:1
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作者 Zicheng ZHAO 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2012年第1期17-32,共16页
Abstract The author introduces the w-function defined on the considered spacelike graph M. Under the growth conditions w = o(log z) and w = o(r), two Bernstein type theorems for M in Rm^n+m are got, where z and r... Abstract The author introduces the w-function defined on the considered spacelike graph M. Under the growth conditions w = o(log z) and w = o(r), two Bernstein type theorems for M in Rm^n+m are got, where z and r are the pseudo-Euclidean distance and the distance function on M to some fixed point respectively. As the ambient space is a curved pseudo- Riemannian product of two Riemannian manifolds (∑1,g1) and (∑2,g2) of dimensions n and m, a Bernstein type result for n =2 under some curvature conditions on E1 and E2 and the growth condition w = o(r) is also got. As more general cases, under some curvature conditions on the ambient space and the growth condition w = o(r) or w = o(√r), the author concludes that if M has parallel mean curvature, then M is maximal. 展开更多
关键词 Product manifold Spacelike graph Parallel mean curvature MAXIMAL BERNSTEIN
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