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arXiv · 2310.09367

Large-eddy simulation of separated flows on unconventionally coarse grids

Yuanwei Bin·George I. Park·Yu Lv·Xiang I. A. Yang
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Abstract

We examine and benchmark the emerging idea of applying the large-eddy simulation (LES) formalism to unconventionally coarse grids where RANS would be considered more appropriate at first glance. We distinguish this idea from very-large-eddy-simulation (VLES) and detached-eddy-simulation (DES), which require switching between RANS and LES formalism. LES on RANS grid is appealing because first, it requires minimal changes to a production code; second, it is more cost-effective than LES; third, it converges to LES; and most importantly, it accurately predicts flows with separation. This work quantifies the benefit of LES on RANS-like grids as compared to RANS on the same grids. Three canonical cases are considered: periodic hill, backward-facing step, and jet in cross flow. We conduct direct numerical simulation (DNS), proper LES on LES grids, LES on RANS-quality grids, and RANS. We show that while the LES solutions on the RANS-quality grids are not grid converged, they are twice as accurate as the RANS on the same grids.

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Yuanwei Bin, George I. Park, Yu Lv, Xiang I. A. Yang. 2023-10-13. Large-eddy simulation of separated flows on unconventionally coarse grids. https://arxiv.org/abs/2310.09367

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