Improved unstructured grid optimization method based on spring analogy

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.