NUMERICAL BOUNDARY-CONDITIONS FOR UNSTEADY TRANSONIC FLOW CALCULATIONS

In calculations of transonic flows it is necessary to limit the domain of computation to a size that is manageable by computers. At the boun dary of the computational domain, boundary conditions are required to ensure a unique solution. Since wave solutions exist in the unsteady t ransonic flow field, incorrect boundary conditions may result in spuri ous reflections from the computational boundary. This may introduce er rors into the solution. To prevent the spurious reflections, absorbing boundary conditions are often used on the computational boundary. In this paper we describe a method to derive absorbing boundary condition s for transonic calculations. We demonstrate both theoretically and nu merically that the use of the absorbing boundary conditions will reduc e the spurious reflections in the calculation.