Effects of non-reflecting boundary conditions on the convergence rate and the size of solution domain

摘要

In this paper effects of boundary conditions at free boundaries and the size of solution domain have been studied. The locations of the boundaries can effect considerably the flow solution. Smaller solution domain causes to reduce the convergence rate and accuracy. The use of non-reflecting boundary conditions (NRBC) at the free boundaries decreases the sensitivity of the solution with regard to the location of the boundaries. In this study, 1-D and 2-D NRBC are used to simulate inviscid flow over a bump, and underexpanded jet. When NRBC is applied to the bump problem, the results show that the number of iterations can be reduced by up to seventy percent and it allows choosing smaller solution domain up to twenty seven percent without loosing accuracy. For the underexpanded jet, the solution diverges when NRBC is not used. It produces converged solution when 1-D NRBC is used, but the results are not accurate. When 2-D NRBC is used, it produces much better results.