An improved spring analogy method for unstructured grid optimization was presented. The method can control the cell density of grid and improve the quality of cells. Non-uniform stiffness spring was used to adjust the cell density of grid in spring analogy method; vertex spring model with revised stiffness and segment spring model with changeable initial balance length were adopted to overcome the drawback of original spring analogy smoothing algorithm

which may lead to local non-smoothness in the grid. The method has kept advantages of original method

such as easy implementation

simple date structure

improved ability of optimization

so the ratio of minimum length to maximum length was updated from 0.24 to 0.42(closer to 1 is better) in the example hereto

helping to optimize the tangled grids also.