带刚性分隔板圆柱绕流控制机理及计算方法研究

Flow around cylinder is a classic problem in fluid mechanics. It must rely on the numerical simulation of N-S equations and turbulence model to simulate the flow field accurately.. Research shows that the standard Galerkin finite element method solving the incompressible Navier-Stokes equations have the following three difficulties: nonlinear effect, incompressibility condition and huge computation.To overcome the above difficulties, a novel finite element method is proposed for the solution of N-S equations. In each time step, the equations are split into the diffusive part, the convective part and the pressure part. The temporal discretization of the convective part is performed by an exact characteristic-Galerkin method. The convective part is solved explicitly and a multistep technique is introduced to enlarge the calculation precision. . The characterstics of flow field of flow past a circular cylinder are studied by the present model, specifically for the case of circular cylinder with a rigid splitter plate. Furthor more, the change of force on cylinder and frequency of vortex shedding based on various lengths and layout schemes are emphatically analysed. It could provides a numerical techonology and methodological support for the practical engineering.

圆柱绕流及其控制是一个经典的流体力学问题，要对其涡流场和压力场进行正确的计算，必须依赖N-S方程及湍流模型的数值求解。. 本项目把N-S方程分裂成扩散项、对流项和压力项，对流项求解采用沿特征线展开的高精度完全显示算法且实现多步法求解，建立求解N-S方程及大涡模拟湍流模型新的有限元方法，克服传统有限元求解非定常不可压N-S方程时存在的非线性效应、不可压缩性约束和计算量大的三大困难。. 用建立的模型对带刚性分隔板圆柱绕流的流场特征展开分析，研究圆柱绕流尾涡演化机制与圆柱受力之间的关系，探讨刚性分隔板长度、布置方式对圆柱受力、旋涡脱落频率的影响，揭示带刚性分隔板圆柱绕流的控制机理，为实际工程提供关键的数值模拟技术和方法支撑。

圆柱绕流及其控制是一个经典的流体力学问题，要对其涡流场和压力场进行正确的计算，必须依赖N-S方程及湍流模型的数值求解。. 本项目把N-S方程分裂成扩散项、对流项和压力项，对流项求解采用沿特征线展开的二阶精度完全显示算法且实现多步法求解，建立求解N-S方程及大涡模拟湍流模型新的有限元方法：基于投影法的特征线算子分裂有限元法。该方法克服传统有限元求解非定常不可压N-S方程时存在的非线性效应、不可压缩性约束和计算量大的三大困难，通过平面Poisseuille流、方腔流和圆柱绕流等经典算例验证了该算法的优越性。. 用本项目建立的模型对圆柱绕流刚性分隔板控制技术进行了研究，得出：1）在低雷诺数下，相对圆柱绕流，带横隔板圆柱绕流的阻力系数、升力系数和斯特劳哈数都减小；2）详细讨论了带横隔板圆柱绕流控制机理，研究了带横隔板圆柱绕流的阻力系数、升力系数和斯特劳哈数都减小的原因；3）随着横隔板长度的增加，漩涡脱落的起点沿流动方向向后推移，在横隔板长为L/D=7时，横隔板完全阻止了圆柱两侧剪切层的相互作用，上下剪切层的涡量在沿横隔板向后推移的过程中已经被耗散殆尽，不再发生漩涡脱落。. 通过该项目的研究，在《力学学报》、《Indian Journal of Engineering & Material Sciences》、《Journal of Applied Mathematics》等期刊上发表论文4篇，在《Computer Modeling in Engineering and Sciences》、《船舶力学》等期刊上录用4篇，在中国科学出版社出版专著1部，获得2项软件著作权，培养在读硕士研究生7名。