共查询到20条相似文献,搜索用时 15 毫秒
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Yu. A. Anikin 《Computational Mathematics and Mathematical Physics》2011,51(11):1923-1932
The two-dimensional rarefied gas flow around a rotating Crookes radiometer and the arising radiometric forces are studied by numerically solving the Boltzmann kinetic equation. The computations are performed in a noninertial frame of reference rotating together with the radiometer. The collision integral is directly evaluated using a projection method, while second- and third-order accurate TVD schemes are used to solve the advection equation and the equation for inertia-induced transport in the velocity space, respectively. The radiometric forces are found as functions of the rotation frequency. 相似文献
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钢管定购和运输的策略优化 总被引:2,自引:0,他引:2
安冉 《数学的实践与认识》2001,31(6):646-653
本文为图 1主管道和图 2树形管道的定购和运输计划给出了一个最优化模型 .通过解这一个最优化模型得到钢管的定购和运输的最优策略 .同时 ,分析了哪个钢厂钢管销价的变化对图 1主管道购运计划和总费用影响最大 ,哪个钢厂钢管产量的上限的变化对购运计划和总费用影响最大 相似文献
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The stability of a drop of liquid hanging from the horizontalcircular mouth of a tube has been investigated by means of thecalculus of variations. Weak perturbations are considered, inwhich the volume of the drop is held constant. It is shown thatthe drop is stable as long as its volume increases with itsheight. 相似文献
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针对问题1,利用微元法证明了面积特性曲线保持线性的必要条件.探索了内筒孔为四种特殊形状下,线性关系比较良好.利用最小二乘原理建立了无约束条件泛函极值模型.通过对内筒孔曲线的合理假设,得到了线性关系较好的内筒孔曲线形状.针对问题2,利用最小二乘原理建立了有约束条件泛函极值模型,设计出最优内筒孔形状.通过牺牲严格的线性关系使其逐渐满足两个约束条件,设计出最优的内筒孔形状.最后考虑外筒孔磨损情况提出了基于自动控制理论和逆向工程技术等方法. 相似文献
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Joshua D. Laison 《Order》2008,25(3):237-242
In 2005, we defined the n-tube orders, which are the n-dimensional analogue of interval orders in 1 dimension, and trapezoid orders in 2 dimensions. In this paper we consider two
variations of n-tube orders: unit n-tube orders and proper n-tube orders. It has been proven that the classes of unit and proper interval orders are equal, and the classes of unit and
proper trapezoid orders are not. We prove that the classes of unit and proper n-tube orders are not equal for all n ≥ 3, so the general case follows the situation in 2 dimensions. 相似文献
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We define the (n,i,f)-tube orders, which include interval orders, trapezoid orders, triangle orders, weak orders, order dimension n, and interval-order-dimension n as special cases. We investigate some basic properties of (n,i,f)-tube orders, and begin classifying them by containment.
Mathematics Subject Classifications (2000) 06A06, 05C62. 相似文献
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本文研究了圆球在半无穷长圆管入口处的蠕动流。得到了速度分布,压力分布和流函数的无穷级数形式的分析解.采用配置法将无穷级数截断并确定出级数中各项系数.求出了均匀入口流绕静止圆球以及圆球以瞬时速度在管内静止流体中运动这两种情形下圆球的阻力系数以及圆球表面上的应力分布.结果表明,当圆球在入口处运动时会遭受到较无穷圆管内为大的阻力.本文还对配置法的收敛性进行了数值实验.试验证明,该法具有好的收敛性. 相似文献
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1969年Lew及Fung[1]计算了圆管内的低雷诸数入口流.1982年Dagan等人[2]得到了有限长圆柱形孔道内蠕动流的级数解.[1]中所得的数值解实质上代表有限长圆管内的低雷诺数入口流,因为一般解中的富氏积分已用富氏级数代替.本文直接计算富氏积分,更精确地求出了真正的半无穷长圆管内Stokes入口流的速度分布,压力分布以及流函数,与此对应的入口段长度为圆管半径的1.2倍,接近于Lew及Fung得到的结果1.3倍.此外,本文还研究了配置法的收敛性,证明了此法在入口流问题中具有很好的收敛性,因此可以在其他类似的问题中采用. 相似文献
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We consider light ray reflections in a d-dimensional semi-infinite tube, for \(d\ge 3\), made of Lambertian material. The source of light is placed far away from the exit, and the light ray is assumed to reflect so that the distribution of the direction of reflected light ray has the density proportional to the cosine of the angle with the normal vector. We present new results on the exit distribution from the tube, and generalizations of some theorems from an earlier article, where the dimension was limited to the cases \(d=2\) and \(d=3\). 相似文献
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Previous work on incompressible composite tubes reinforced bywire-layers and subject to pressure is extended to compressibletubes. Explicit formulae are found for stresses in the wire-layerswhen their Young's moduli are much greater than the moduli ofthe layers, and are found to depend crucially on the compressibilityor incompressibility of the interior layers. Numerical resultsare given for the "bursting pressure" for a tube reinforcedby two and three double wire layers. 相似文献
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A theoretical analysis is given for a composite tube, reinforcedby extensible wire layers and subject to pure bending by endcouples and flexure by end shear forces. 相似文献
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We have developed a numerical method for simulating viscous flow through a compliant closed tube, driven by a pair of fluid source and sink.
As is natural for tubular flow simulations, the problem is formulated in axisymmetric cylindrical coordinates, with fluid flow described by the Navier-Stokes equations.
Because the tubular walls are assumed to be elastic, when stretched or compressed they exert forces on the fluid. Since these forces are singularly
supported along the boundaries, the fluid velocity and pressure fields become unsmooth. To accurately
compute the solution, we use the velocity decomposition approach, according to which pressure and velocity are decomposed into a singular part and a remainder part.
The singular part satisfies the Stokes equations with singular boundary forces.
Because the Stokes solution is unsmooth, it is computed to second-order accuracy
using the immersed interface method, which incorporates known jump discontinuities
in the solution and derivatives into the finite difference stencils.
The remainder part, which satisfies the Navier-Stokes equations with a continuous
body force, is regular.
The equations describing the remainder part are discretized in time using
the semi-Lagrangian approach, and then solved using
a pressure-free projection method.
Numerical results indicate that the computed overall solution is second-order
accurate in space, and the velocity is second-order accurate in time. 相似文献