Evaluation of an improved mixing plane interface for OpenFOAM

A mixing plane interface provides a circumferentially averaging rotor-stator coupling interface, which is extremely useful in practical turbomachinery simulations. It allows fundamentally transient problems to be studied in steady-state, using simplified mesh components having periodic properties, and with the help of a multiple reference frames (MRF) approach. An improved version of the mixing plane interface for the community-driven version of OpenFOAM is presented. This new version of the mixing plane introduces a per- field, user-selectable mixing option for the flow fields at the interface, including the possibility to use a mass-flow averaging algorithm for the velocity field. We show that the quality of the mass-flow transfer can be improved by a proper selection of the mixing options at the interface. This paper focuses on the evaluation of the improved mixing plane interface for various steady-state simulations of incompressible flows, applied to a simple 2D validation test case, and to more complex 3D turbomachinery cases