基于虚拟弹性体的快速动网格方法

An Efficient Dynamic Mesh Method Based on Pseudo Elastic Solid

为减少流固耦合的计算时间,在现有弹性体方法的基础上,发展了一种快速动网格方法。首先根据弹性体方法的基本假设,将流场网格所包围的空间区域视为虚拟弹性体,然后将结构与该虚拟弹性体视为一个整体系统,并计算其固有振动的振型及频率,最后以结构受到的流体作用力为激励,通过振型叠加法计算结构网格及流场网格节点的位移。考虑到实际结构的流固耦合振动多为低阶模态的振动,在流固耦合计算中可以通过低阶模态的叠加计算流场网格节点的位移,从而达到快速更新流场网格的目的。采用该快速动网格算法,对某弹性梁颤振问题进行了流固耦合分析,计算结果与已有文献的结果吻合很好,说明了该算法的正确性。与现有的弹性体方法相比,该算法使流固耦合计算时间减少了65.5%。对Wing 445.6模型的颤振问题进行了分析,得到颤振边界与实验值吻合良好,且与现有弹性体法相比,可以减少计算时间54.8%。

To reduce the computing time of fluid structure coupling, an efficient dynamic mesh method based on the pre-existing elastic solid method is developed. The flow mesh domain is assumed to be a pseudo elastic solid according to the basic hypotheses of the elastic solid method, then the structure and the pseudo elastic solid are considered together as one holistic system. Subsequently the natural frequencies and vibration modes are calculated for the system and the flow force acted on the structure is considered as the excitation of the holistic system. The nodal displacements for the structure and the flow mesh are computed by mode superposition. In fact, the actual fluid structure coupled vibration for structures often appears associated with low order modes, the nodal displacements of the flow mesh can be calculated by modal superposition of the first few of low order modes, thus the flow mesh can be updated efficiently. A beam flutter problem is discussed with the present dynamic mesh method. The results coincide well with the data reported in the existing reference verifying the validation of the present method. The computing time is reduced by 65.5% compared with the pre-existing elastic solid method. The flutter of wing 445.6 is also analyzed and the calculated flutter experimental data, and the computing time is reduced by 54. 8%.