期刊文献+
共找到35篇文章
< 1 2 >
每页显示 20 50 100
广义流体的概念在金属流动凝固传热分析模型中的应用 被引量:7
1
作者 金珠梅 赫冀成 邸洪双 《计算物理》 CSCD 北大核心 1999年第4期409-413,共5页
应用广义流体的概念,以双辊连续铸轧工艺中金属流动凝固传热现象为例,将熔池内三种状态(液相、固相和固液两相)金属流动传热过程用统一的控制方程描述。典型算例表明:熔池内存在大面积的环形流动区域,环形流动产生的搅拌效应,可... 应用广义流体的概念,以双辊连续铸轧工艺中金属流动凝固传热现象为例,将熔池内三种状态(液相、固相和固液两相)金属流动传热过程用统一的控制方程描述。典型算例表明:熔池内存在大面积的环形流动区域,环形流动产生的搅拌效应,可以促进熔池内钢水温度与化学成分的均化,提高薄带的质量。最后,计算结果与理论分析进行了比较。该计算思想还可应用于冶金。 展开更多
关键词 数值模拟 广义流体 凝固传热 金属流体
下载PDF
土力学的新概念与土骨架 被引量:8
2
作者 蒙理明 《建材世界》 2017年第3期96-102,共7页
该文用土力学的新概念改善和细化了土骨架理论。土骨架的3要素有:土颗粒,包括其结合水;接触(点或面);联接(收缩膜,公共结合水膜)。土颗粒相互接触,或相互联接,或即相互接触又联接构成土骨架。土骨架溃散指土颗粒即没有接触也没有联接。... 该文用土力学的新概念改善和细化了土骨架理论。土骨架的3要素有:土颗粒,包括其结合水;接触(点或面);联接(收缩膜,公共结合水膜)。土颗粒相互接触,或相互联接,或即相互接触又联接构成土骨架。土骨架溃散指土颗粒即没有接触也没有联接。结合水膜联接最强,其次到收缩膜联接,最弱是接触。土骨架局部失去接触或联接为损伤;溃散或损伤的土骨架重新建立接触或联接为修复,还伴有加密的为增强。饱和土的土骨架体积,是包括结合水膜的土颗粒体积;非饱和土的土骨架体积,是包括结合水膜的土颗粒,加上收缩膜联接的体积。土是由土骨架和广义流体组成的,与非饱和土有效应力的大气张力公式相对应。应该用绝对压强分析广义流体。有效应力的新概念也可以描述为:有效应力是土骨架的接触和联接所对应的应力;总应力由有效应力和广义流体应力组成;有效应力的实质是广义流体没有抗剪能力,但具有抗压能力;应该用总应力模式分析土的压缩变形。分析了泥浆干缩、流沙陷阱、地基压缩变形及渗流固结、特殊土灾变、地震灾害的土骨架;还有人工增强土骨架(地基处理)。 展开更多
关键词 新概念 有效应力 土骨架 接触 收缩膜和结合水膜联接 广义流体 绝对压强
下载PDF
双辊铸轧区内流动凝固传热的有限元模拟 被引量:1
3
作者 王文明 钟掘 《矿冶工程》 CAS CSCD 北大核心 2007年第2期61-63,67,共4页
将铸轧区内处于不同状态的金属视为广义流体,实现了铸轧区流动凝固传热过程的统一数学描述,建立了铸轧区等效厚度几何模型和有限元模型,提出了热流密度沿铸轧方向线性递减分布的宏观假设,并运用有限元法对计算模型进行了耦合求解,揭示... 将铸轧区内处于不同状态的金属视为广义流体,实现了铸轧区流动凝固传热过程的统一数学描述,建立了铸轧区等效厚度几何模型和有限元模型,提出了热流密度沿铸轧方向线性递减分布的宏观假设,并运用有限元法对计算模型进行了耦合求解,揭示了铸轧区内温度场的分布规律,对合理制定铸轧工艺规程具有重要参考价值。 展开更多
关键词 双辊铸轧 温度场 有限元 广义流体
下载PDF
An exact solution of unsteady Couette flow of generalized second grade fluid 被引量:17
4
作者 TAN Wenchang XIAN Feng WEI Lan 《Chinese Science Bulletin》 SCIE EI CAS 2002年第21期1783-1785,共3页
The fractional calculus approach is introduced into the rheological constitutive model of a generalized second grade fluid. A constitutive model with fractional derivative is developed for the generalized second grade... The fractional calculus approach is introduced into the rheological constitutive model of a generalized second grade fluid. A constitutive model with fractional derivative is developed for the generalized second grade fluid. Unsteady Couette flow of the generalized second grade fluid is studied by using the method of the discrete inverse Laplace transform and generalized Mittag-Leffler function. And then an exact solution is obtained for this problem with arbitrary fractional derivative. This provides a new analytical tool for the study of viscoelastic fluid mechanics. 展开更多
关键词 FRACTIONAL CALCULUS UNSTEADY COUETTE flow generalized second grade fluid EXACT solution.
原文传递
UNSTEADY FLOWS OF A GENERALIZED SECOND GRADE FLUID WITH THE FRACTIONAL DERIVATIVE MODEL BETWEEN TWO PARALLEL PLATES 被引量:19
5
作者 谭文长 徐明喻 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2004年第5期471-476,共6页
The fractional calculus approach in the constitutive relationship model of a generalized second grade fluid is introduced.Exact analytical solutions are obtained for a class of unsteady flows for the generalized secon... The fractional calculus approach in the constitutive relationship model of a generalized second grade fluid is introduced.Exact analytical solutions are obtained for a class of unsteady flows for the generalized second grade fluid with the fractional derivative model between two parallel plates by using the Laplace transform and Fourier transform for fractional calculus.The unsteady flows are generated by the impulsive motion or periodic oscillation of one of the plates.In addition,the solutions of the shear stresses at the plates are also determined. 展开更多
关键词 fractional derivative unsteady flows generalized second grade fluid parallel plates
下载PDF
非牛顿流体搅拌流场的数值模拟研究进展 被引量:12
6
作者 张敏革 张吕鸿 +1 位作者 姜斌 李鑫钢 《化工进展》 EI CAS CSCD 北大核心 2009年第8期1296-1301,共6页
对非牛顿流体搅拌流场数值模拟过程中的控制方程、旋转桨叶的处理以及数值计算方法三个方面进行了综合论述。阐述了广义牛顿流体模型形式简单、计算量低,在非牛顿流体搅拌流场数值模拟过程中应用广泛;黏弹性流体本构方程具有高度的非线... 对非牛顿流体搅拌流场数值模拟过程中的控制方程、旋转桨叶的处理以及数值计算方法三个方面进行了综合论述。阐述了广义牛顿流体模型形式简单、计算量低,在非牛顿流体搅拌流场数值模拟过程中应用广泛;黏弹性流体本构方程具有高度的非线性,采用计算流体力学(CFD)方法对其搅拌流场进行数值模拟难度较高,目前仍处于起步阶段;通过合理简化黏弹性流体本构方程以及采用恰当的数值离散方法,有助于在黏弹性流体的搅拌流场数值模拟中取得进展。 展开更多
关键词 非牛顿流体 搅拌流场 广义牛顿流体模型 黏弹性流体
下载PDF
广义二阶流体涡流速度的衰减和温度扩散 被引量:8
7
作者 沈芳 谭文长 +1 位作者 赵耀华 T.增冈隆士 《应用数学和力学》 EI CSCD 北大核心 2004年第10期1053-1060,共8页
 将分数阶微积分运算引入到二阶流体的本构关系中,建立了带分数阶导数的广义二阶流体模型· 研究了广义二阶流体涡流速度的衰减和温度扩散,利用分数阶导数的Laplace变换和广义Mittag_Leffler函数,得到了涡流速度场和温度场的精...  将分数阶微积分运算引入到二阶流体的本构关系中,建立了带分数阶导数的广义二阶流体模型· 研究了广义二阶流体涡流速度的衰减和温度扩散,利用分数阶导数的Laplace变换和广义Mittag_Leffler函数,得到了涡流速度场和温度场的精确解。 展开更多
关键词 广义二阶流体 分数阶微积分 涡流 温度场 广义Mittag-Leffler函数
下载PDF
气体压力对气辅共挤成型界面的影响 被引量:7
8
作者 柳和生 邓小珍 +2 位作者 黄益宾 黄兴元 赖家美 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2014年第3期119-123,共5页
将气体简化为广义牛顿流体,并作为单独一层,针对矩形气辅共挤口模,建立了三维粘弹有限元模型,对理论模型进行了数值计算,研究了气体压力对气辅共挤成型界面形貌的影响及形成稳定气垫层所需最小气体压力与气垫层厚度和熔体流率的关系。... 将气体简化为广义牛顿流体,并作为单独一层,针对矩形气辅共挤口模,建立了三维粘弹有限元模型,对理论模型进行了数值计算,研究了气体压力对气辅共挤成型界面形貌的影响及形成稳定气垫层所需最小气体压力与气垫层厚度和熔体流率的关系。研究表明,当稳定气垫层形成后,随着气压力或气垫层厚度的增大,共挤制品挤出胀大率减小,粘性包围程度增大;形成稳定气垫层所需的最小气体压力随气垫层厚度的增大而减小,随着熔体流率的增大而增大。 展开更多
关键词 气辅共挤 气垫层 牛顿流体 界面形貌 数值模拟
下载PDF
一种广义牛顿流体的广义黏度模型 被引量:5
9
作者 宋维宁 林祥 任冬云 《中国塑料》 CAS CSCD 北大核心 2009年第12期26-30,共5页
针对广义牛顿流体提出了一种具有普遍意义的广义黏度模型,该模型以应力张量和应变速率张量的不变量表示,并根据应变速率张量的第二、第三不变量相互独立性,使该模型不但满足黏度的惟一性,还符合剪切变稀及各种拉伸形态的黏度模型,并能... 针对广义牛顿流体提出了一种具有普遍意义的广义黏度模型,该模型以应力张量和应变速率张量的不变量表示,并根据应变速率张量的第二、第三不变量相互独立性,使该模型不但满足黏度的惟一性,还符合剪切变稀及各种拉伸形态的黏度模型,并能够应用于既有剪切又有拉伸的一般复合流动。当模型用于简单稳态的剪切流动或稳态拉伸流动时,则得到各自的剪切黏度或拉伸黏度,并与目前定义的剪切黏度和拉伸黏度一致。因此,对广义牛顿流体所有形态的流动,该黏度模型都适用。 展开更多
关键词 剪切黏度 拉伸黏度 广义牛顿流体 广义黏度 惟一性
下载PDF
On the MHD flow of fractional generalized Burgers' fluid with modified Darcy's law 被引量:5
10
作者 T.Hayat M.Khan S.Asghar 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2007年第3期257-261,共5页
This work is concerned with applying the fractional calculus approach to the magnetohydrodynamic (MHD) pipe flow of a fractional generalized Burgers' fluid in a porous space by using modified Darcy's relationship.... This work is concerned with applying the fractional calculus approach to the magnetohydrodynamic (MHD) pipe flow of a fractional generalized Burgers' fluid in a porous space by using modified Darcy's relationship. The fluid is electrically conducting in the presence of a constant applied magnetic field in the transverse direction. Exact solution for the velocity distribution is developed with the help of Fourier transform for fractional calculus. The solutions for a Navier-Stokes, second grade, Maxwell, Oldroyd-B and Burgers' fluids appear as the limiting cases of the present analysis. 展开更多
关键词 Modeling generalized Burgers' fluid Fractional calculus Exact solution
下载PDF
基于三维有限元模拟的聚合物复合型材共挤出过程分析 被引量:6
11
作者 张敏 黄传真 +1 位作者 孙胜 贾玉玺 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2009年第10期98-101,105,共5页
建立了两种聚合物熔体在圆柱形流道中共挤出流动的三维数值计算模型,采用有限元方法数值模拟了复合棒材(LDPE/PS)的共挤出成形过程,并对共挤出界面的形状、入口与出口的速度、流动过程的压力降以及入口流量对界面的影响等进行了分析。... 建立了两种聚合物熔体在圆柱形流道中共挤出流动的三维数值计算模型,采用有限元方法数值模拟了复合棒材(LDPE/PS)的共挤出成形过程,并对共挤出界面的形状、入口与出口的速度、流动过程的压力降以及入口流量对界面的影响等进行了分析。结果表明,在对接棒材的共挤出过程中,当入口流量相同时,共挤出界面偏向低黏度熔体一侧;入口流量较小的变化即引起共挤出界面的形状与位置较大的变动,在对接棒材的成形过程中为获得稳定的流动,须严格控制入口流量的变化。最后将数值计算得到的界面与实验结果进行了对比,表明数值计算的结果与实验结果是一致的。 展开更多
关键词 广义牛顿流体 共挤出 有限元模拟 复合型材
下载PDF
具有霍尔效应的广义Maxwell流体通过无穷平板的旋转MHD流动和传热
12
作者 乔艳丽 续焕英 齐海涛 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2024年第5期17-32,共16页
黏弹性流体的流动和传热特性研究一直是一个备受关注的问题.然而,一些黏弹性流体的行为会偏离由整数阶控制方程描述的经典的流动和传热现象.因此,建立一种新的本构关系来研究复杂黏弹性流体是有必要的.本文研究了霍尔效应作用下具有分... 黏弹性流体的流动和传热特性研究一直是一个备受关注的问题.然而,一些黏弹性流体的行为会偏离由整数阶控制方程描述的经典的流动和传热现象.因此,建立一种新的本构关系来研究复杂黏弹性流体是有必要的.本文研究了霍尔效应作用下具有分布阶特性的广义Maxwell流体在无穷平板上的旋转磁流体流动和传热现象.考虑到广义Maxwell流体流动和传热的多尺度特性和非局部性,引入分数阶微积分理论准确地描述流动和传热机理,导出了由时间分布阶动量方程和时间分数阶能量方程组成的分数阶控制方程.为了计算速度和温度控制方程的数值解,我们基于L1近似公式提出了Crank-Nicolson有限差分格式,然后,验证了数值方法的有效性和可行性,并以图形形式讨论了相关参数对流体速度和温度的影响,给出了一些结论. 展开更多
关键词 MAXWELL流体 霍尔效应 有限差分格式 黏弹性流体 近似公式 流体速度 局部性 能量方程
原文传递
Some exact solutions of the oscillatory motion of a generalized second grade fluid in an annular region of two cylinders 被引量:4
13
作者 A.Mahmood C.Fetecau +1 位作者 N.A.Khan M.Jamil 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第4期541-550,共10页
The velocity field and the associated shear stress corresponding to the longitudinal oscillatory flow of a generalized second grade fluid, between two infinite coaxial circular cylinders, are determined by means of th... The velocity field and the associated shear stress corresponding to the longitudinal oscillatory flow of a generalized second grade fluid, between two infinite coaxial circular cylinders, are determined by means of the Laplace and Hankel transforms. Initially, the fluid and cylinders are at rest and at t = 0+ both cylinders suddenly begin to oscillate along their common axis with simple harmonic motions having angular frequencies Ω1 and Ω2. The solutions that have been obtained are presented under integral and series forms in terms of the generalized G and R functions and satisfy the governing differential equation and all imposed initial and boundary conditions. The respective solutions for the motion between the cylinders, when one of them is at rest, can be obtained from our general solutions. Furthermore, the corresponding solutions for the similar flow of ordinary second grade fluid and Newtonian fluid are also obtained as limiting cases of our general solutions. At the end, the effect of different parameters on the flow of ordinary second grade and generalized second grade fluid are investigated graphically by plotting velocity profiles. 展开更多
关键词 generalized second grade fluid Velocity field Shear stress Longitudinal oscillatory flow Laplace and Hankel transforms
下载PDF
微孔塑料挤出成型中气泡长大过程的数值模拟 被引量:3
14
作者 麻向军 黄晨 《塑料科技》 CAS 北大核心 2009年第3期67-70,共4页
选用广义牛顿流体等温条件下气泡长大的细胞模型,并利用Polyflow软件的用户自定义模块编制发泡成型口模中泡孔半径及熔体密度的计算模块,可实现微孔塑料挤出口模中气泡长大过程的数值模拟。
关键词 超临界CO2 气泡长大 可压缩流体 广义牛顿流体 数值模拟
下载PDF
分数阶广义二阶流体管内轴向流动的精确解 被引量:1
15
作者 金辉 徐明瑜 《山东大学学报(理学版)》 CAS CSCD 北大核心 2003年第1期23-27,共5页
研究了分数阶广义二阶流体的管内轴向流动问题 .在欧氏测度下 ,应用R L分数阶微积分算子理论给出了上述问题的精确解 .同时也指出了已有文献结果的错误和不足之处 .结果表明 ,流体粘弹性特征越明显 。
关键词 广义二阶流体 轴向流动 分数阶微积分 广义M-L函数
下载PDF
Exact solutions of MHD second Stokes flow of generalized Burgers fluid 被引量:1
16
作者 M.KHAN R.MALIK A.ANJUM 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第2期211-224,共14页
This work concerns with the exact solutions of magnetohydrodynamic(MHD)flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distr... This work concerns with the exact solutions of magnetohydrodynamic(MHD)flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distribution and shear stress are expressed as a combination of steady-state and transient solutions computed by means of integral transformations. The effects of various parameters on the flow field are investigated. The MHD flow results in reduction of velocity distribution and associated thickness of the boundary layer. 展开更多
关键词 generalized Burgers fluid magnetohydrodynamic(MHD) flow porous medium exact solution
下载PDF
DECAY OF VORTEX VELOCITY AND DIFFUSION OF TEMPERATURE IN A GENERALIZED SECOND GRADE FLUID
17
作者 沈芳 谭文长 +1 位作者 赵耀华 T.增冈隆士 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2004年第10期1151-1159,共9页
The fractional calculus approach in the constitutive relationship model of viscoelastic fluid was introduced. The velocity and temperature fields of the vortex flow of a generalized second fluid with fractional deriva... The fractional calculus approach in the constitutive relationship model of viscoelastic fluid was introduced. The velocity and temperature fields of the vortex flow of a generalized second fluid with fractional derivative model were described by fractional partial differential equations. Exact analytical solutions of these differential equations were obtained by using the discrete Laplace transform of the sequential fractional derivatives and generalized Mittag-Leffler function. The influence of fractional coefficient on the decay of vortex velocity and diffusion of temperature was also analyzed. 展开更多
关键词 generalized second grade fluid fractional calculus unsteady flow temperature field generalized Mittag-Leffler function
下载PDF
An inverse problem to estimate an unknown order of a Riemann-Liouville fractional derivative for a fractional Stokes' first problem for a heated generalized second grade fluid 被引量:2
18
作者 Bo Yu Xiaoyun Jiang Haitao Qi 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2015年第2期153-161,共9页
In this paper,we propose a numerical method to estimate the unknown order of a Riemann-Liouville fractional derivative for a fractional Stokes' first problem for a heated generalized second grade fluid.The implicit n... In this paper,we propose a numerical method to estimate the unknown order of a Riemann-Liouville fractional derivative for a fractional Stokes' first problem for a heated generalized second grade fluid.The implicit numerical method is employed to solve the direct problem.For the inverse problem,we first obtain the fractional sensitivity equation by means of the digamma function,and then we propose an efficient numerical method,that is,the Levenberg-Marquardt algorithm based on a fractional derivative,to estimate the unknown order of a Riemann-Liouville fractional derivative.In order to demonstrate the effectiveness of the proposed numerical method,two cases in which the measurement values contain random measurement error or not are considered.The computational results demonstrate that the proposed numerical method could efficiently obtain the optimal estimation of the unknown order of a RiemannLiouville fractional derivative for a fractional Stokes' first problem for a heated generalized second grade fluid. 展开更多
关键词 Riemann-Liouville fractional derivative generalized second grade fluid Inverse problem Implicit numerical method Fractional sensitivity equation
下载PDF
Some Exact Solutions of Generalized Jeffrey Fluid Using N-Transform
19
作者 Amir Khan Gul Zaman +1 位作者 Saeed Ahmad M. Ikhlaq Chohan 《American Journal of Computational Mathematics》 2017年第4期402-412,共11页
In this paper, we presents some new exact solutions corresponding to three unsteady flow problems of a generalized Jeffrey fluid produced by a flat plate between two side walls perpendicular to the plate. The fraction... In this paper, we presents some new exact solutions corresponding to three unsteady flow problems of a generalized Jeffrey fluid produced by a flat plate between two side walls perpendicular to the plate. The fractional calculus approach is used in the governing equations. The exact solutions are established by means of the Fourier sine transform and N-transform. The series solutions of velocity field and associated shear stress in terms of Fox H-function, satisfying all imposed initial and boundary conditions, have been obtained. The similar solutions for ordinary Jeffrey fluid, performing the same motion, appear as limiting case of the solutions are also obtained. Also, the obtained results are analyzed graphically through various pertinent parameters. 展开更多
关键词 generalized Jeffrey fluid FRACTIONAL DERIVATIVES FOX H-Functions N-Transform
下载PDF
Exact solution of electroosmotic flow in generalized Burgers fluid
20
作者 T.HAYAT S.AFZAL A.HENDI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2011年第9期1119-1126,共8页
An exact solution is developed for the time periodic electroosmotic flow of a non-Newtonian fluid between the micro-parallel plates.The constitutive equations of a generalized Burgers fluid are used in the mathematica... An exact solution is developed for the time periodic electroosmotic flow of a non-Newtonian fluid between the micro-parallel plates.The constitutive equations of a generalized Burgers fluid are used in the mathematical formulation.The resulting problem is solved by a Fourier transform technique.Graphs are plotted and discussed for various emerging parameters of interest. 展开更多
关键词 generalized Burgers fluid periodic flow Fourier transform
下载PDF
上一页 1 2 下一页 到第
使用帮助 返回顶部