Inflow turbulence generation for eddy-resolving simulations of turbomachinery flows

TL;DR

This paper introduces a robust inflow turbulence generation method for unstructured grid CFD simulations, validated on turbulent boundary layers and applicable to turbomachinery flows, improving inflow condition accuracy.

Contribution

A novel rescaling algorithm based on momentum thickness is proposed, simplifying inflow turbulence generation for unstructured grid CFD codes and extending to hybrid RANS/LES approaches.

Findings

Validated on flat plate turbulent boundary layer simulations.

Demonstrated utility in annular diffuser flow simulations.

Enhanced robustness and simplicity over existing methods.

Abstract

A simple variant of recycling and rescaling method to generate inflow turbulence using unstructured grid CFD codes is presented. The method has been validated on large eddy simulation of spatially developing flat plate turbulent boundary layer. The proposed rescaling algorithm is based on the momentum thickness which is more robust and essentially obviates the need of finding the edge of the turbulent boundary layer in unstructured grid codes. Extension of this algorithm to hybrid RANS/LES type of approaches and for wall-bounded turbomachinery flows is also discussed. Results from annular diffuser with different inflow boundary layer characteristics is presented as an example application to show the utility of such an algorithm.