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局部热壁面多孔介质方腔内自然对流的数值研究 总被引:1,自引:0,他引:1
本文对上下壁面绝热、左侧壁面长度为b的嵌装加热器部分维持恒定温度T_h而剩余部分绝热,且右侧壁面维持恒定温度T_c的多孔介质方腔内的自然对流换热进行了数值研究.在热壁面无量纲长度B=0.5(B=b/L)的条件下,综合研究了左侧壁面受热部分中心距上壁面的无量纲长度D(D=d/L)、Da数、Ra数和孔隙率对腔体内自然对流换热的影响.数值计算结果表明,左侧壁面受热部分位置的不同对腔体内自然对流换热有很大的影响,D在0.6附近取值时,Na数最大.Da数、Ra数对腔体的自然对流换热影响较大,而孔隙率对换热的影响较小. 相似文献
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为了对比研究弱可压光滑粒子动力学(WCSPH)方法和不可压光滑粒子动 力学(ISPH)方法在模拟封闭方腔自然对流问题时的特性, 采用粒子位移技术有效地解决了高瑞利数条件下, 拉格朗日型SPH方法模拟封闭方腔自然对流时流体域内的粒子聚集和空穴问题, 将拉格朗日型SPH 方法求解封闭方腔自然对流问题的最高瑞利数提高到了106; 进而通过对比瑞利数分别为104, 105, 106的条件下, 采用拉格朗日型WCSPH、 拉格朗日型ISPH、欧拉型ISPH三种SPH方法模拟得到的封闭方腔速度分布云图、 温度分布云图、壁面努赛尔特数分布曲线和平均努塞尔特数, 分析了三种SPH方法在模拟封闭方腔自然对流时的精度、稳定性和计算效率. 结果表明: 在低瑞利数条件下, 以上三种SPH方法都可以较好地模拟此问题, 在高瑞利数条件下, 欧拉型ISPH方法的模拟结果最为精确; 拉格朗日型WCSPH方法模拟所得结果比拉格朗日型ISPH方法模拟所得结果稍好些.
关键词:
光滑粒子动力学
不可压光滑粒子动力学
粒子位移技术
自然对流 相似文献
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复杂多孔介质腔体内自然对流换热的数值研究 总被引:1,自引:1,他引:0
采用曲线坐标系下压力与速度耦合的SIMPLEC算法,数值研究复杂多孔介质腔体内的自然对流换热问题.腔体的曲面温度分别保持恒定,上下表面绝热.在曲线坐标系中用有限容积法离散方程,并采用Brinkman扩展达西模型及局部非热平衡模型求解,综合研究Rayleigh数,Darcy数、孔隙率等参数对腔体内自然对流换热的影响.计算结果表明:Rayleigh数和Darcy数的影响最大而孔隙率的影响很小,同时存在使得腔体内换热达到最强的最佳纵横比. 相似文献
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通过泰勒展式系数匹配的方法发展了基于非等距网格的有限容积紧致格式,采用延迟修正的方法建立了基于SIMPLE的紧致方法,,该方法能够得到高精度的数值解,增加迭代求解代数方程组的稳定性。对底部加热的方腔内自然对流换热问题进行数值模拟,结果表明,紧致方法比二阶中心差分方法具有更高的精度。 相似文献
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The paper presents an iterative algorithm for studying a nonlinear shallow-water wave equation. The equation is written as an evolution equation, involving only first-order spatial derivatives, coupled with the Helmholtz equation. We propose a two-step iterative method that first solves the evolution equation by the implicit midpoint rule and then solves the Helmholtz equation using a three-point sixth-order compact scheme. The first-order derivative terms in the first step are approximated by a sixth-order dispersion-relation-preserving scheme that preserves the physically inherent dispersive nature. The compact Helmholtz solver, on the other hand, allows us to use relatively few nodal points in a stencil, while achieving a higher-order accuracy. The midpoint rule is a symplectic time integrator for Hamiltonian systems, which may be a preferable method to solve the spatially discretized evolution equation. To give an assessment of the dispersion-preserving scheme, we provide a detailed analysis of the dispersive and dissipative errors of this algorithm. Via a variety of examples, we illustrate the efficiency and accuracy of the proposed scheme by examining the errors in different norms and providing the rates of convergence of the method. In addition, we provide several examples to demonstrate that the conserved quantities of the equation are well preserved by the implicit midpoint time integrator. Finally, we compare the accuracy, elapsed computing time, and spatial and temporal rates of convergence among the proposed method, a complete integrable particle method, and the local discontinuous Galerkin method. 相似文献
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在等离子体平衡重建迭代计算过程中,需要快速求解Grad-Shafranov方程(G-S方程)。构造了具有四阶精度紧致差分格式的离散方程,采用离散正弦变换技术对其进行快速求解并采用CUDATM实现GPU并行加速,将其应用到EAST等离子体平衡重建PEFIT代码中,实现基于紧致差分格式的快速G-S方程求解。结果表明,在65×65的网格下,给定方程右端项电流分布的前提下,使用GPU求解G-S方程所需时间为大约34μs。 相似文献
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This paper makes some numerical comparisons of time–space iterative method and spatial iterative methods for solving the stationary Navier–Stokes equations. The time–space iterative method consists in solving the nonstationary Stokes equations based on the time–space discretization by the Euler implicit/explicit scheme under a weak uniqueness condition (A2). The spatial iterative methods consist in solving the stationary Stokes scheme, Newton scheme, Oseen scheme based on the spatial discretization under some strong uniqueness assumptions. We compare the stability and convergence conditions of the time–space iterative method and the spatial iterative methods. Moreover, the numerical tests show that the time–space iterative method is the more simple than the spatial iterative methods for solving the stationary Navier–Stokes problem. Furthermore, the time–space iterative method can solve the stationary Navier–Stokes equations with some small viscosity and the spatial iterative methods can only solve the stationary Navier–Stokes equations with some large viscosities. 相似文献
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求解Navier-Stokes方程组的组合紧致迎风格式 总被引:1,自引:0,他引:1
给出一种新的至少有四阶精度的组合紧致迎风(CCU)格式,该格式有较高的逼近解率,利用该组合迎风格式,提出一种新的适合于在交错网格系统下求解Navier-Stokes方程组的高精度紧致差分投影算法.用组合紧致迎风格式离散对流项,粘性项、压力梯度项以及压力Poisson方程均采用四阶对称型紧致差分格式逼近,算法的整体精度不低于四阶.通过对Taylor涡列、对流占优扩散问题和双周期双剪切层流动问题的计算表明,该算法适合于对复杂流体流动问题的数值模拟. 相似文献
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The generalized ZK–BBM equation is solved using iterative scheme of the Adomian decomposition method (ADM) and variational iteration method (VIM). A dark and a kink soliton solutions of the generalized ZK–BBM equation are obtained under initial conditions. The convergence analysis of the ADM and VIM solution shows that these solutions are convergent. The comparison of the ADM and VIM solutions with the exact solution shows that the solutions of the generalized ZK–BBM equation by the iterative methods are almost exact. The absolute errors show that the accuracy and efficiency of the ADM and VIM depend on the problem and its domain. It is found that the iterative scheme of Adomian decomposition method and variational iteration method are quite efficient for the soliton solution of the generalized ZK–BBM equation. 相似文献
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Qun Lin & Wujian Peng 《advances in applied mathematics and mechanics.》2012,4(4):473-482
An acceleration scheme based on stationary
iterative methods is presented for solving linear system of equations. Unlike Chebyshev semi-iterative method
which requires accurate estimation of the bounds for iterative matrix
eigenvalues, we use a wide range of Chebyshev-like polynomials for
the accelerating process without estimating the bounds of the
iterative matrix. A detailed error analysis is presented and convergence rates are obtained.
Numerical experiments are carried out and comparisons with classical Jacobi and Chebyshev semi-iterative methods
are provided. 相似文献
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Yongbin Ge 《Journal of computational physics》2010,229(18):6381-6391
A fourth-order compact difference discretization scheme with unequal meshsizes in different coordinate directions is employed to solve a three-dimensional (3D) Poisson equation on a cubic domain. Two multgrid methods are developed to solve the resulting sparse linear systems. One is to use the full-coarsening multigrid method with plane Gauss–Seidel relaxation, which uses line Gauss–Seidel relaxation to compute each planewise solution. The other is to construct a partial semi-coarsening multigrid method with the traditional point or plane Gauss–Seidel relaxations. Numerical experiments are conducted to test the computed accuracy of the fourth-order compact difference scheme and the computational efficiency of the multigrid methods with the fourth-order compact difference scheme. 相似文献