Numerical analysis of a high-order unstructured overset grid method for compressible LES of turbomachinery

Abstract

Large-Eddy Simulation (LES) is recognized as a promising method for highfidelity flow predictions in turbomachinery applications. The presented approach consists of the coupling of several instances of the same LES unstructured solver through an overset grid method. A high-order interpolation, implemented within this coupling method, is introduced and evaluated on several test cases. It is shown to be third order accurate, to preserve the accuracy of various second and third order convective schemes and to ensure the continuity of di↵usive fluxes and subgrid scale tensors even in detrimental interface configurations. In this analysis, three types of spurious waves generated at the interface are identified. They are significantly reduced by the high-order interpolation at the interface. The latter having the same cost as the original lower order method, the high-order overset grid method appears as a promising alternative to be used in all the applications.

Turbomachinery Noise Predictions: Present and Future

“…The first instance computes the flow field across the first row, while the second one handles the second one. High-order interpolation have also been implemented to preserve the solver scheme accuracy [76].…”

Towards the Large-Eddy Simulation of a full engine: Integration of a 360 azimuthal degrees fan, compressor and combustion chamber. Part I: Methodology and initialisation

“…When it applies, the transfer of the flow between the static and rotating sub-domains is performed with an overset grid method over a common geometrical zone for the proper exchange of the necessary information (Wang et al, 2014;de Laborderie et al, 2018). AVBP is based on the SPMD paradigm for parallelism (Single Program -Multiple Data).…”

“…The addition of another AVBP instance for the combustion chamber was also tested on a sectoral configuration but it led to an increase in computational cost of over 20% due to the additional instance and its new interfaces. Ultimately, the solution retained for this work was to generate a 360 degrees coarse mesh that was then refined following a given metric using the library MMG (Dapogny et al, 2014;Daviller et al, 2017). To refine and adapt the mesh, a metric is constructed using the meshes from the stand-alone sectoral simulations as the target mesh (Figure 3a), and using the 360 degrees coarse mesh as input (Figure 3b).…”

Wall-Modeled Large-Eddy Simulations of a Multistage High-Pressure Compressor

“…Since the overlapping cells are not coincident, data are interpolated at each exchange. MISCOG was originally developed with a spatially second order accurate interpolation [54] and has recently been extended with a third order accurate interpolation, using nodal gradients and the Hermite polynomial technique [24]. As recommended, this high-order interpolation is used in all simulations presented.…”

“…It is indeed a fully unstructured solver. Besides the rotor-stator interface treatment has been thoroughly evaluated in [54,24] and shown to comply with requirements for an accurate LES. Finally the AVBP solver includes high-order numerical schemes already validated and widely used in different applications.…”