中文摘要：

对鱼类等柔性变形体的数值模拟需要解决如下几个问题：（1）柔性体动态网格生成；（2）基于动态网格的不可压流非定常算法。本文基于Delaunay背景网格插值方法，发展了一套快速生成柔性体变形的动态混合网格生成方法；对于不可压流问题，采用虚拟压缩方法进行求解，结合双时间步方法来处理非定常问题；最后数值模拟了鱼体巡游的非定常流动，分析了鱼体的摆动频率对力、功耗等流体动力学特性的影响。

英文摘要：

Recently, research on bio-fluid dynamics has become widespread all over the world. For swimming fish, their bodies deform flexibly with moving, and the flows around them are strongly unsteady. To simulate the unsteady flows over swimming fishes, dynamic grid technique and corresponding flow solver should be set up firstly. In this paper, a hybrid dynamic grid technique based on Delaunay background grid technique and local remeshing is presented firstly. In order to carry out bio-fluid simulations, an incompressible Navier-Stokes numerical solver on the hybrid dynamic grid is presented also based on the artificial compressibility method with dual-time stepping for time advancing. Finally we simulate the unsteady flows of the swimming fish with different phase speeds. The influence of the phase speed （C） on the flow structures and force characteristics are analyzed. The total drag decreases monotonically as C exceeds a threshold value, which means the fish is propelled by thrust. The results increases and becomes negative when C agree very well with those of references.