A new dynamic grid method based on an unstructured background mesh is proposed in this article. Firstly, a relatively thin unstructured background mesh was generated by a small amount of surface nodes; secondly, spring analogy method was used to calculate the movement of background mesh nodes caused by boundary movement; thirdly, the movement of computing mesh nodes were interpolated using their position in the background mesh; finally, the movement of surface nodes and thick nodes near them were corrected when the surface is curly. By reducing the solving scale of the spring analogy, the efficiency of mesh deformation was increased effectively. Additionally, the quality of the dynamic mesh can be improved, since using improved spring analogy method and unstructured background mesh can transfer the movement of internal nodes more evenly. Examples show the feasibility and efficiency of this method.%借鉴弹簧动网格方法和Delaunay背景图方法,提出一种基于非结构背景网格的动网格生成方法.先用少量的物面控制点生成相对较粗的非结构背景网格,再用弹簧法将动边界的变化量作用到该背景网格,然后利用计算网格与背景网格的映射关系插值生成对应的动网格,最后对物面网格点及其附近受影响的密网格点进行局部网格修正,获得最终计算所需的动网格.所提方法与直接弹簧法比较,由于弹簧法作用的背景网格远粗于实际的计算网格,提高了计算效率,此外,由于网格的运动受控于受弹簧法作用的背景网格,边界变形或运动能较为均匀地传递到内部网格上,使网格单元过渡光滑,提高了动网格的质量.给出若干算例,展示了方法的效率和可行性.
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