| 1. | Convergence is accelerated by means of local time stepping , implicit residual smoothing . the numerical results have been obtained for the flows over n ac ago 12 or rae2822 airfoils
并且基于点云离散结构，引入了当地时间步长、残值光顾等加速收敛技术，数值模拟了对称和非对称翼型绕流，获得较好的计算结果。 |
| 2. | In order to accelerate the convergence , residual smoothing and local time stepping were employed . in the same time , by improving prolongation operator , a new multi - grid scheme which can combine well with the algorithm of this thesis
为加速计算收敛速度，除了采用当地时间步长和局部残差光顺技术外，通过改造插值算子，提出了一种能够与本文算法很好地结合的多重网格法。 |
| 3. | In order to accelerate the convergence speed , we employ the local time step , and implicit residual smoothing methods . finally , we use this method to get the steady solution of the flow around naca0012 and naca4412 airfoil at very low speed and some basic unsteady solution
本文对在低马赫数下绕naca0012翼型和naca4412翼型的定常流场进行了求解，结果和实验基本吻合，并对非定常运动情况进行了初步模拟研究，得出了一些有意义的结果。 |
| 4. | 4 . a 2 - d and 3 - d euler equations and n - s equations are solved using the cell - centered finite volume method and four - step runge - kutta scheme on the cartesian grids with standard convergence acceleration techniques such as local time stepping , enthalpy and implicit residual smoothing
使用jameson中心有限体积法和runge - kutta时间推进方法，求解了关于二维、三维复杂流场的euler 、 navier - stokes方程，采用了当地时间步长、隐式残值光顺等多种加速收敛方法。 |
| 5. | The viscid flux is discretized by second - order central difference scheme . baldwin - lomax turbulence model is implemented in navier - stokes flow solver . for steady - state calculations , a four - stage runge - kutta scheme with convergence acceleration techniques such as local - time stepping and implicit residual smoothing is used
其中，定常计算中的时间推进采用四步runge ? kutta方法，并应用了当地时间步长、隐式残值光顺等加速收敛措施；非定常计算中的时间推进采用jameson的隐式双时间方法。 |
| 6. | The explicit method is widely used for its simpleness and little memory consumed with local time step and variable coefficients implicit residual smooth to accelerate the convergence procedure . according to yoon and jameson ' s ideas , an efficient implicit lu - sgs algorithm is carefully constructed by combing the advantages of lu factorization and symmetric - gauss - seidel technique in such a way to make use the l and u operators scalar diagonal matrices , thus the numeric algorithm requires only scalar inversion . the computational efficiency is greatly improved with this scheme
显式方法具有简单，消耗内存小等优点，并采用当地时间步长、变系数隐式残值光顺等加速收敛措施，在定常流动的模拟中得到了广泛的应用;根据yoon和jameson提出的简化正、负矩阵分裂，构造的l 、 u算子只需进行标量对角阵求逆，极大提高了流场数值求解过程的计算效率;采用newton类型的伪时间子迭代技术使时间推进精度提高至二阶。 |
| 7. | In this paper , the upwind scheme and the central scheme are presented for solving 3 - d n - s equations using the cell - center finite volume spatial discretization and four - stage runge - kutta time stepping scheme , with standard convergence acceleration techniques such as local time stepping and implicit residual smoothing
在n - s方程的数值计算上，采用了中心差分格式和迎风格式，用格心格式的有限体积法进行了空间离散，用四步龙格?库塔法作显式时间推进，并采用了当地时间步长和隐式残差光顺等加速收敛措施。 |
| 8. | The cell - centered symmetric finite volume arithmetic and runge - kutta time stepping scheme are performed to solve euler equation . the two order and four order artificial dissipation is introduced for stability , local time stepping and implicit residual smoothing technique is applied to save computer time
在求解euler方程方面，采用格心格式的有限体积法进行空间离散，四步runge - kutta法作时间推进，二阶、四阶人工耗散作为稳定措施，还采用当地时间步长和隐式残值光顺提高收敛速度。 |
