A method for generating and optimizing arbitrary three-dimensional boundary-conforming computational grids has been developed. The smoothness and local orthogonality of the grid are maximized using a fast iterative procedure, and provision is made for clustering the optimized grid in selected regions. An optimal grid can be obtained iteratively, irrespective of the method used to generate the initial grid. Unacceptable grids and even singular grids (i. e. - grids containing regions of overlap) can be made useful for computation using this method. Application of the method to several test cases shows that grids containing regions of overlap are typically untangled in two to five iterations, and that the conjugate gradient optimization procedure converges to an optimal grid within fifty iterations. Taking advantage of the original properties of this method, a new concept for generating optimal three-dimensional computational grids is proposed.lt consists in optimizing a first guess of the desired grid, using an imperfect grid generated by a simple, inexpensive method as input.
