A Nonlinear Reduced Order Method with Overset Adaptive Cartesian/Unstructured Grid for Moving Body Simulation

摘要

This paper will demonstrate an innovative hybrid nonlinear reduced order method (ROM) for deforming unstructured mesh and an overset Cartesian grid for moving body problems. By utilizing the properties of a maximum 6 degrees of freedom (DOF) of a moving body, the newly proposed method computes the grid deformation using nonlinear large deformation theory to preserve the original grid quality under each DOF. This ensures that no extra computations are required during the unsteady motion, other than just matrix-vector multiplications. The deformation of unstructured grid around store is shown to be very efficient with minimum grid distortion. The introduction of the overset Cartesian method is shown to provide the flexibility when dealing with extremely large deformations and deterioration of grid quality. The present method has the merits of reduced grid distortion, minimum modification to an existing code, efficient moving grid methodology with simple matrix multiplication, and minimized needs of hole-cutting and donor cell searching of overset grid. This paper will show the testing of each individual components of the method, including nonlinear ROM for unstructured deformation and overset Cartesian grid for coupling with an unstructured grid.