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为了适用于柔性变形、相对运动等复杂动边界问题,建立了并行环境下重叠和变形相结合的动态混合网格生成技术.通过计算区域分解以及分布式并行实现了重叠和变形技术的结合,其中重叠网格采用了并行化的隐式装配方法,并发展了两种并行化查询策略.变形网格则采用了并行化的径向基函数(RBF)插值方法.并行化动态网格生成方法大幅提高了动态网格生成效率,有利于处理大规模的动边界问题.在此基础上,发展了基于变形/重叠动态混合网格的流动/运动/控制一体化数值模拟方法,进一步改进了耦合模拟软件平台——HyperFLOW.典型应用算例证明了该动态混合网格技术及一体化算法的实用性. 相似文献
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提出一种并行求解不规则区域上的Poisson方程方法,将不规则区域转化为带约束的三维结构网格表示,在该区域采用红黑排序并行求解Poisson方程.数值实验表明,方法可较好地解决不规则区域上的Poisson并行求解问题.同时评估了不规则区域对并行性能带来的影响. 相似文献
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依据温度标量场与动量计算的空间和时间计算分辨率不同的特点,采用两套网格,建立多分辨率双网格并行直接求解方法,用以解决极高Ra数湍流热对流DNS模拟巨大计算工作量的难题.在两套网格的数据交换上,根据每个细网格都满足连续方程,设计了速度的守恒平移插值方法.二维极高Ra数湍流热对流的计算结果表明,采用多分辨率双网格并行直接求解方法的DNS计算,可以使计算工作量降低近一个量级.瞬时温度场显示,双网格方法的计算结果可以很好地描述极高Ra数下快速运动的小尺寸漩涡团状羽流,得到的结果与原网格一致,不同方法计算得到的传热Nu数误差不超过1%. 相似文献
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针对二维泊松方程在实际应用过程中几种常用方法存在计算量大、易发散、局部收敛等不足,提出了一种改进算法.该算法基于并行超松弛迭代法,采用遗传算法对松弛因子进行全局寻优,解决了超松弛迭代法求解泊松方程时最佳松弛因子难以确定的问题.构建了多目标适应度函数,优化了遗传算子参数,分析了算法的计算量、计算时间与误差精度,与传统方法进行了对比研究.结果表明:松弛因子对泊松方程求解的速度与精度影响显著;改进算法能减少迭代次数,节省计算时间,加快方程的求解;算法适合于求解计算量较大、精度要求较高的时域有限差分方程,而且精度要求越高,算法的性能越好,节省的时间也越多. 相似文献
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为了解决基于第一性原理分析计算大尺度量子输运体系时遇到的耗时长久问题,挖掘密度泛函理论与非平衡格林函数相结合方法(DFT+NEGF方法)在自洽迭代过程中的计算热点,就计算电子密度矩阵时的能量点积分和计算格林函数时的矩阵求逆/乘法运算提出MPI/Open MP并行计算方案.能量点积分采用MPI多进程并行方案,在数据初始化时需要将稀疏矩阵和积分能量点依照轮询调度算法分配给各进程.矩阵求逆/乘法的并行化既可调用ScaLAPACK子程序实现又可调用IntelMKL数学库中的OpenMP多线程加速函数实现.由于不同能量点计算的独立性,能量点积分采用的MPI并行计算获得近乎线性的加速比曲线.由于Open MP多线程并行采用的是基于共享内存的数据交换机制以及线程间切换通信开销小,矩阵求逆/乘法运算的OpenMP并行实现在计算效率上要优于而在程序的可扩展性上要劣于MPI多进程并行实现. 相似文献
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激波与火焰面相互作用数值模拟的GPU加速 总被引:1,自引:0,他引:1
为考察计算机图形处理器(GPU)在计算流体力学中的计算能力,采用基于CPU/GPU异构并行模式的方法对激波与火焰界面相互作用的典型可压缩反应流进行数值模拟,优化并行方案,考察不同网格精度对计算结果和计算加速性能的影响.结果表明,和传统的基于信息传递的MPI 8线程并行计算相比,GPU并行模拟结果与MPI并行模拟结果相同;两种计算方法的计算时间均随网格数量的增加呈线性增长趋势,但GPU的计算时间比MPI明显降低.当网格数量较小时(1.6×104),GPU计算得到的单个时间步长平均时间的加速比为8.6;随着网格数量的增加,GPU的加速比有所下降,但对较大规模的网格数量(4.2×106),GPU的加速比仍可达到5.9.基于GPU的异构并行加速算法为可压缩反应流的高分辨率大规模计算提供了较好的解决途径. 相似文献
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三维多群中子扩散方程的精确、高效求解是核动力堆芯设计及燃料管理的基础。应用有限差分方法求解该方程具有简便、精确、成熟的优点;然而,该方法的计算量和存储量均较大,极大地限制了它的计算规模和应用范围。本文基于大规模并行计算,研究三维多群中子扩散方程有限差分方法:采用中心有限差分格式离散中子扩散方程;基于MPI并行编程模型,采用空间区域分解的方式实现大规模并行计算;采用多群多区域耦合PGMRES算法进行并行加速。在集群服务器上开发了ParaFiDi程序,并采用IAEA3D,PHWR等多个基准题对该程序进行验证。数值结果表明,ParaFiDi程序具有较高的计算精度和计算效率。 相似文献
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Comparison between numerical simulation and experimental results for unsteady flow field in a radial diffuser pump is presented
for the design operating point. The numerical result is obtained by solving three-dimensional, unsteady Reynolds-averaged
Navier-Stokes equations by the commercial CFD code CFX-10 withk-ω based shear stress transport turbulence model. Two-dimensional PIV measurements are conducted to acquire the experiment
result. The phase-averaged velocity and turbulent kinetic energy fields are compared in detail between the results by the
two methods in the impeller, diffuser and return channel regions. The qualitative comparison between CFD and PIV results is
quite good in the phase-averaged velocity field. Although the turbulence level by PIV is higher than that by CFD generally,
the main turbulence features are nearly the same. Furthermore, the blade orientation effect and other associated unsteady
phenomena are also examined, in order to enhance the understanding on impeller-diffuser interaction in a radial diffuser pump. 相似文献
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煤灰沉积的传热过程模型及其数值研究 总被引:6,自引:0,他引:6
计算流体力学(CFD)方法的应用在锅炉设计或燃烧设备的改造过程中有着十分重要的作用.本文研究了实际燃烧过程中普遍存在的煤灰沉积现象对数值计算结果的影响,提出了描述煤灰沉积的新型传热模型,比较了新模型采用前后数值计算结果与实测数据的差异,从而验证了该模型的合理性,提高了对炉内积灰、结渣过程数值描述的精度. 相似文献
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基于蒙特卡罗程序JMCT2.2和商用CFD程序FLUENT,通过C++语言,采用外耦合的方式开发了一套耦合接口程序。利用JMCT网格和FLUENT计算域之间一一映射的方式完成物理模型和CFD模型之间的网格匹配,实现了物理模型的简单划分和CFD模型网格的精细划分。利用该耦合程序计算了压水堆单根燃料棒模型和3×3带水洞的燃料子组件模型,并与MCNP与FLUENT耦合计算结果进行对比。计算结果表明,使用本文的方法,耦合JMCT程序与FLUENT程序能够用于物理-热工耦合计算并准确提供其反馈参数。 相似文献
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Direct numerical simulation (DNS) of complex flows require solving the problem on parallel machines using high accuracy schemes. Compact schemes provide very high spectral resolution, while satisfying the physical dispersion relation numerically. However, as shown here, compact schemes also display bias in the direction of convection – often producing numerical instability near the inflow and severely damping the solution, always near the outflow. This does not allow its use for parallel computing using domain decomposition and solving the problem in parallel in different sub-domains. To avoid this, in all reported parallel computations with compact schemes the full domain is treated integrally, while using parallel Thomas algorithm (PTA) or parallel diagonal dominant (PDD) algorithm in different processors with resultant latencies and inefficiencies. For domain decomposition methods using compact scheme in each sub-domain independently, a new class of compact schemes is proposed and specific strategies are developed to remove remaining problems of parallel computing. This is calibrated here for parallel computing by solving one-dimensional wave equation by domain decomposition method. We also provide the error norm with respect to the wavelength of the propagated wave-packet. Next, the advantage of the new compact scheme, on a parallel framework, has been shown by solving three-dimensional unsteady Navier–Stokes equations for flow past a cone-cylinder configuration at a Mach number of 4.Additionally, a test case is conducted on the advection of a vortex for a subsonic case to provide an estimate for the error and parallel efficiency of the method using the proposed compact scheme in multiple processors. 相似文献
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A predictive method is proposed to determine the transmission loss of reactive silencers using the three-dimensional (3-D) time-domain computational fluid dynamics (CFD) approach and the plane wave decomposition technique. Firstly, a steady flow computation is performed with a mass-flow-inlet boundary condition, which provides an initial condition for the following two unsteady flow computations. The first unsteady flow computation is conducted by imposing an impulse (acoustic excitation) superimposed on the constant mass flow at the inlet of the model and then adding the non-reflecting boundary condition (NRBC) when the impulse completely propagates into the silencer. The second unsteady flow computation is conducted for the case without acoustic excitation at the inlet. The time histories of pressure and velocity at the upstream monitoring point as well as history of pressure at the downstream monitoring point are recorded during the two transient computations. The differences between the two unsteady flow computational results are the corresponding acoustic quantities. Therefore, the incident sound pressure signal is obtained by using plane wave decomposition at upstream, while the transmitted sound pressure signal is just the sound pressure at downstream. Finally, those two sound pressure signals in the time-domain are transformed into the frequency-domain by Fast Fourier Transform (FFT) and then the transmission loss (TL) of silencer is determined. For the straight-through perforated tube silencers with and without flow, the numerical results agree well with the published measurements. 相似文献
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通过ANSYS CFX对ITER屏蔽块进行了热工水力分析,对同一计算模型给出了两套不同的网格,分析了网格对计算精度的影响,结果表明两套网格都有较好的计算精度。通过数值模拟分析了壁面粗糙度对流动及传热的影响,结果表明壁面粗糙度是影响传热的一个非常重要的因素。 相似文献
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通过ANSYS CFX对ITER屏蔽块进行了热工水力分析,对同一计算模型给出了两套不同的网格,分析了网格对计算精度的影响,结果表明两套网格都有较好的计算精度。通过数值模拟分析了壁面粗糙度对流动及传热的影响,结果表明壁面粗糙度是影响传热的一个非常重要的因素。 相似文献