Development of grid movement algorithms suitable for aerodynamic optimization.

摘要

Two new grid movement algorithms have been developed and implemented in the aerodynamic shape optimization software Optima2D, OptimaMB and Optima3D for 2- and 3-dimensional analysis. The algorithms are based on the spring analogy and linear elasticity methods. The former uses a stiffening parameter to enhance element stiffness near the deforming boundary while the latter uses inhomogeneous material properties with a stiffening mechanism based on element distortion to control mesh deformation. Additionally, a fast element stiffness matrix procedure is adopted to increase the efficiency of its computation. The displacements of the internal nodes are solved for using the conjugate-gradient method with an incomplete lower-upper (ILU) preconditioner.; Large deformation tests are performed to compare the efficiency and robustness of the two methods. The algorithms are also used in several optimization cases, and the results are compared with those obtained using the existing algebraic grid perturbation method. For all cases, the linear elasticity method is the most robust, although it is also the most computationally expensive.