Stability Analysis of Intermediate Boundary Conditions in Approximate Factorization Schemes

The paper discusses the role of the intermediate boundary condition in the AF2 scheme used by Holst for simulation of the transonic full potential equation. We show that the treatment suggested by Holst led to a restriction on the time step and suggest ways to overcome this restriction. The discussion is based on the theory developed by Gustafsson, Kreiss, and Sundstrom and also on the von Neumann method. Research for the third author was supported in part by the National Aeronautics and Space Administration under NASA Contract Nos. NASI-17070 and NASI-18107 and under AFOSR 85-0303 while he was in residence at the Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, Hampton, VA 23665-5225. i