Hierarchical geometry modelling using the immersed boundary method

Abstract

The Immersed Boundary Method has been used to simulate a range of fundamental flows and turbulence. Such studies have demonstrated the method’s promising applicability for engineering analysis. However, to the authors’ knowledge, flows in coupled components or in scenarios with coupled physics, such as rotor–stator interaction, fan–intake interaction, aeroelastics, aeroacoustics, etc., are still rarely investigated using high-fidelity methods. Due to its high computational costs, the complexity of geometry meshing process and the requirement for moving boundaries limit the investigation of flows in such environments. Previous research suggests that high-fidelity simulations with an acceptable geometry modelling strategy may tackle these issues and provide useful insights. There exists a hierarchy of geometry modelling methods which includes the conventional Directly Mesh Resolving (DMR) method, the Immersed Boundary Method (IBM), and the IBM with Smeared Geometry (IBMsg, or eIBMg). The present research proposes an alternative to these approaches in the form of the Euler IBM with local force (eIBMl) by imposing a distribution function generated from blade configuration. Compared to the eIBMg, this method can include more realistic flow physics within each blade passage without smearing its geometry. This method is applied to the study of fan–intake interaction focusing on the transport of inlet distortion through blade passages and pressure wave propagation.