WALL BOUNDARY-CONDITIONS FOR HIGH-ORDER FINITE-DIFFERENCE SCHEMES IN COMPUTATIONAL AEROACOUSTICS

High-order finite-difference schemes are less dispersive and dissipati ve but, at the same time, more isotropic than low-order schemes. They are well suited for solving computational acoustics problems. High-ord er finite-difference equations, however, support extraneous wave solut ions which bear no resemblance to the exact solution of the original p artial differential equations. These extraneous wave solutions, which invariably degrade the quality of the numerical solutions, are usually generated when solid-wall boundary conditions are imposed. A set of n umerical boundary conditions simulating the presence of a solid wall f or high-order finite-difference schemes using a minimum number of ghos t values is proposed. The effectiveness of the numerical boundary cond itions in producing quality solutions is analyzed and demonstrated by comparing the results of direct numerical simulations and exact soluti ons.