A DUAL-TIME METHOD FOR THE SOLUTION OF THE UNSTEADY EULER EQUATIONS

A ''dual-time'' method for solving the three-dimensional Euler equatio ns describing the compressible flow about wings undergoing arbitrary m otions and deformations is presented. A finite-volume formulation is c hosen where the volumes distort as the wing moves or deforms. Independ ent motion of the inner and outer boundaries of the grid is permitted with a sequence of grids generated using transfinite interpolation. An implicit real-time discretisation is used, and the equations are inte grated in a fictitious pseudo time. This approach allows the real-time step to be chosen on the basis of accuracy rather than stability. It also permits the acceleration techniques commonly used to speed up ste ady flow calculations to be used when marching in pseudo time, without compromising real-time accuracy. A two-dimensional version of the met hod has also been developed and results for both two and three-dimensi onal transonic flows are presented and compared with experimental data where available.