Mathematical Formulation of 3D Non‐Reflecting Boundary Conditions for Hyperbolic Equations for Internal Flows in Thermal Engines

This article presents the development of inlet/outlet non‐reflecting boundary conditions for solving partial differential equations, applied on internal flows. The proposed method is based on Fourier decomposition of the outgoing characteristics at the inflow and outflow boundaries. The influence of non‐reflecting boundary conditions on the accuracy of the flow field predictions is evaluated. Computations carried out reveal that convergence to steady state is reached faster when non‐reflecting boundary conditions are used compared to the reflecting type. In case of unsteady flows, it has been found that non‐reflecting boundary conditions absorb pressure waves incident to the inlet and outlet planes without creating any reflection that could contaminate the solution.