A dual-time method for the solution of the unsteady Euler equations

Abstract A “dual-time” method for solving the three-dimensional Euler equations describing the compressible flow about wings undergoing arbitrary motions and deformations is presented. A finite-volume formulation is chosen where the volumes distort as the wing moves or deforms. Independent 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 integrated 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 steady flow calculations to be used when marching in pseudo time, without compromising real-time accuracy. A two-dimensional version of the method has also been developed and results for both two and three-dimensional transonic flows are presented and compared with experimental data where available.