共查询到18条相似文献,搜索用时 78 毫秒
1.
发展了一种基于高精度和高效格式计算悬停旋翼复杂绕流的隐式有限体积方法。控制方程为Euler方程,其中对流项通量的左右状态量采用五阶加权基本无振荡(WENO)格式重构,时间推进应用隐式LU-SGS算法,为进一步加速收敛,采用三层V循环多重网格松弛方法。考虑到多重网格方法的思想以及五阶WENO格式涉及6个网格单元,建议仅在最细网格上使用WENO格式。计算结果表明本文方法能有效捕捉激波,对尾迹也有较高分辨率,基于隐式LU-SGS算法的多重网格方法能有效提高计算效率。 相似文献
2.
研究了Kirchhoff积分面是否有盖有底,以及是否计及旋翼网格上的流场值,这两个因素对噪声预测结果的影响.发展了一种基于重叠网格的计算悬停旋翼远场噪声的数值方法.数值计算过程分为流场模拟和声场模拟两部分.悬停旋翼流场的数值模拟是在两个相互重叠的网格上进行的:在高质量的旋翼网格上求解Navier-Stokes方程,用于模拟旋翼附近的粘性流动和近场尾涡的捕捉;在远离粘性区域处布置符合悬停流场物理特征的圆柱形背景网格,控制方程为Euler方程,用于远场尾涡的捕捉.计算得到的流场信息插值到用于声场计算的Kirchhoff积分面上.观测点处的噪声可以认为是由这个完全包含桨叶的Kirchhoff积分面上的面元(声源)发声得到.远场声波的传播由Kirchhoff积分公式描述.计算结果表明:采用有盖有底的Kirchhoff积分面并且同时计及旋翼网格流场值时,计算得到的HSI噪声与实验值吻合最好. 相似文献
3.
4.
旋翼结构参数及动力学参数对旋翼动力学特性有着重要影响。随着旋翼结构型式的不断更新,在旋翼设计中需要考虑的动力学参数也相应增加,从而使旋翼的动力学问题更加复杂化。本文通过在2米旋翼试验台上进行的试验,用测量桨叶频响函数和稳态响应的方法研究了悬停状态预锥角、预掠角和总距角等旋翼结构参数对桨叶固有特性及气动弹性稳定性的影响规律,并同计算结果进行了比较,得到了一些对旋翼设计有实用意义的结论 相似文献
5.
6.
将计算量小,激波分辨率高的AUFS (artificially upstream flux vector splitting) 格式应用于无网格方法. 所发展算法基于多项式基函数最小二乘无网格方法,采用线性基函数曲面拟合及AUFS 格式计算各离散点的空间导数,应用四阶Runge-Kutta 法进行时间显式推进. 为验证算法健壮性、精度以及计算效率,对Riemann 问题、超音速平面流动,以及不同攻角NACA0012 翼型跨音速流场进行了数值模拟,其结果同采用HLLC (Harten-Lax-van Leer-contact) 格式的无网格方法以及文献报道结果吻合较好,并且计算量较形式简单HLLC 格式减少约15%. 相似文献
7.
最近, 基于非结构网格的高阶通量重构格式(flux reconstruction, FR)因其构造简单且通用性强而受到越来越多人的关注. 但将FR格式应用于大规模复杂流动的模拟时仍面临计算开销大、求解时间长等问题. 因此, 亟需发展与之相适应的高效隐式求解方法和并行计算技术. 本文提出了一种基于块Jacobi迭代的高阶FR格式求解定常二维欧拉方程的单GPU隐式时间推进方法. 由于直接求解FR格式空间和隐式时间离散后的全局线性方程组效率低下并且内存占用很大. 而通过块雅可比迭代的方式, 能够改变全局线性方程组左端矩阵的特征, 克服影响求解并行性的相邻单元依赖问题, 使得只需要存储和计算对角块矩阵. 最终将求解全局线性方程组转化为求解一系列局部单元线性方程组, 进而又可利用LU分解法在GPU上并行求解这些小型局部线性方程组. 通过二维无黏Bump流动和NACA0012无黏绕流两个数值实验表明, 该隐式方法计算收敛所用的迭代步数和计算时间均远小于使用多重网格加速的显式Runge-Kutta格式, 且在计算效率方面至少有一个量级的提升. 相似文献
8.
采用浸没边界格子Boltzmann (immersed boundary-lattice Boltzmann, IB-LB)模型执行动边界绕流数值模拟时,信息交互界面和边界力计算格式直接影响流动求解器的数值精度和计算效率.基于隐式扩散界面,一种改进的直接力格式IB-LB模型被提出.边界力表达式基于欧拉/拉格朗日变量同一性准则推导,转换矩阵描述的信息交互界面耦合了拉格朗日节点间的非同步运动.采用Richardson迭代数值求解关联边界力与无滑移速度约束的线性方程组,不仅克服了传统速度修正格式中矩阵求逆引起的计算效率问题,而且摆脱了算法稳定性对拉格朗日点分布的依赖.根据解析解已知的Taylor-Green涡流评估本文模型的数值模拟精度,结果表明改进的IB模型能够完整保留背景LB模型的二阶数值精度.静止圆柱和振荡圆柱绕流数值实验结果表明,当前模型在涉及复杂外形和运动界面的流动模拟中能够提供可靠的数值预测,满足力同一性的IB-LB模型能够有效抑制非定常流体力的伪物理震荡.波动翼型绕流模拟验证了当前模型的实用性,可在大变形柔性体流固耦合动力学问题中进一步推广. 相似文献
9.
10.
11.
Numerical experiments with several variants of the original weighted essentially non‐oscillatory (WENO) schemes (J. Comput. Phys. 1996; 126 :202–228) including anti‐diffusive flux corrections, the mapped WENO scheme, and modified smoothness indicator are tested for the Euler equations. The TVD Runge–Kutta explicit time‐integrating scheme is adopted for unsteady flow computations and lower–upper symmetric‐Gauss–Seidel (LU‐SGS) implicit method is employed for the computation of steady‐state solutions. A numerical flux of the variant WENO scheme in flux limiter form is presented, which consists of first‐order and high‐order fluxes and allows for a more flexible choice of low‐order schemes. Computations of unsteady oblique shock wave diffraction over a wedge and steady transonic flows over NACA 0012 and RAE 2822 airfoils are presented to test and compare the methods. Various aspects of the variant WENO methods including contact discontinuity sharpening and steady‐state convergence rate are examined. By using the WENO scheme with anti‐diffusive flux corrections, the present solutions indicate that good convergence rate can be achieved and high‐order accuracy is maintained and contact discontinuities are sharpened markedly as compared with the original WENO schemes on the same meshes. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
12.
By the aid of an idea of the weighted ENO schemes, some weight-type high-resolution difference schemes with different orders
of accuracy are presented in this paper by using suitable weights instead of the minmod functions appearing in various TVD
schemes. Numerical comparisons between the weighted schemes and the non-weighted schemes have been done for scalar equation,
one-dimensional Euler equations, two-dimensional Navier-Stokes equations and parabolized Navier-Stokes equations.
The project supported by the National Natural Science Foundation of China (19582007) and Partly by State Key Laboratory of
Scientific/Engineering Computing. 相似文献
13.
《Wave Motion》2020
In this paper we proposed the kinetic framework based fifth-order adaptive finite difference WENO schemes abbreviated as WENO-AO-K schemes to solve the compressible Euler equations, which are quasi-linear hyperbolic equations that can admit discontinuous solutions like shock and contact waves. The formulation of the proposed schemes is based on the kinetic theory where one can recover the Euler equations by applying a suitable moment method strategy to the Boltzmann equation. The kinetic flux vector splitting strategy is used in WENO-AO framework, which produces the computationally expensive error and exponential functions. Thus, to reduce the computational cost, a physically more relevant peculiar velocity based splitting strategy is used, which is more efficient than the kinetic flux vector splitting. High order of accuracy in time is achieved using the third-order total variation diminishing Runge–Kutta (TVD-RK) scheme. Several one- and two-dimensional test cases are solved for the compressible Euler equations using the proposed fifth-order WENO-AO-K schemes and the results are compared with conventional WENO-AO scheme. Proposed schemes capture the complex flow features in a smooth region accurately, and discontinuity is also well resolved. Error analysis of the proposed schemes shows optimal convergence rates in various norms. 相似文献
14.
C. B. Allen 《国际流体数值方法杂志》2003,41(9):931-949
An upwind Euler solver is presented, and applied to multibladed lifting hovering rotor flow. These flows can be simulated as a steady case, in a blade‐fixed rotating co‐ordinate system. However, forward flight simulation will always require an unsteady solution. Hence, as a stepping stone in the development of a forward flight simulation tool, both explicit steady and implicit unsteady simulations of the same hovering case are presented. Convergence of the two approaches is examined and compared, in terms of residual history, cost, and solution evolution, as a means of both validating the unsteady formulation and considering implications for forward flight simulation. Consideration of the solution evolution and wake capturing shows that for hovering rotor cases, the unsteady and steady solutions are the same, but the unsteady solution is more expensive in terms of CPU time. It is also shown that for hover, the fewer real time‐steps taken per revolution the more efficient the implicit scheme is. However, this is a characteristic of the case, which results in smooth solution variation between time steps. It is also demonstrated that for rotary flow simulation, the global residual is not a useful quantity to assess convergence. The residual reaches a very low (constant in the implicit case) value while the solution is still evolving. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
15.
16.
This paper presents a detailed study on the implementation of Weighted Essentially Non‐Oscillatory (WENO) schemes on GPU. GPU implementation of up to ninth‐order accurate WENO schemes for the multi‐dimensional Euler equations of gas dynamics is presented. The implementation detail is discussed in the paper. The computational times of different schemes are obtained and the speedups are reported for different number of grid points. Furthermore, the execution times for the main kernels of the code are given and compared with each other. The numerical experiments show the speedups for the WENO schemes are very promising especially for fine grids. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
17.
Shunsuke Kurioka David R. Dowling 《International Journal of Computational Fluid Dynamics》2013,27(3):233-243
Three-dimensional dynamic gas–liquid flow simulations that accurately track the phase interface are numerically challenging. This article presents a numerical study of the performance of the level-set phase–interface tracking method when combined with extremely high order (7th to 11th) weighted essentially non-oscillatory (WENO) advection schemes for gas–liquid free surface flows. Comparisons between simulation results and prior benchmark results suggest that such a combination of methods can be satisfactorily applied to the level-set and Navier-Stokes equations for free surface flow simulations when volume conservation is enforced at every time step, and minor numerical oscillations are suppressed through use of an artificial viscosity term. In particular, simulations of solid body rotation, the unsteady flow following an ideal dam break, tank sloshing, and the rise of a single bubble all agree with analytical or experimental results to within ± 3.12% when the level-set method is combined with an 11th order WENO scheme. Furthermore, use of an 11th order WENO advection scheme actually has a computational cost advantage because, for the same accuracy, it can be used on a coarser grid when compared with a more-common second-order advection scheme; computational savings of up to 87% are possible. 相似文献