The characteristic boundary condition in pressure-based methods

This article deals with the implementation of the characteristic boundary condition, also known as the pressure far field boundary condition, in segregated pressure-based flow solvers. This boundary condition applies the Riemann invariants to determine the flow variables at domain inlets and outlets. The newly developed method is implemented in a cell-centered unstructured grid code following a finite volume discretization. Testing is performed by solving the following problems: turbulent flow over a flat plate; inviscid transonic flow over a circular are bump; inviscid supersonic flow over three equidistant circular arc bumps; turbulent flow over an axisymmetric transonic bump; turbulent flow over a NACA 0012 airfoil at 10 degrees angle of attack; and turbulent flow over the three-dimensional ONERA M6 wing at 3.06 degrees angle of attack. Predictions with the current pressure-based solver are compared with similar ones generated using a density-based method and with experimental data. Results are in excellent agreement.