Hybrid RANS/LES/DNS of turbulence flow along a flat plate

Abstract

Contemporarily, direct numerical simulation (DNS), Large-eddy simulation (LES), and Reynolds-averaged Navier-Stokes (RANS) are the three most mature Computational fluid dynamics (CFD) used methods for turbulence simulations. The calculation accuracy and difficulty of these three models are decreased in order. For the sale of finding a balance between the accuracy of the results and the efficiency, we tried to combine these three models. In this paper, for an adiabatic and incompressible flow, we use DNS, LES, and RANS at first. After analyzing their results, a time-space relationship is obtained. First, for a fixed time point, the flow field is divided into three parts by the distance from the wall. Secondly, a long-term simulation is performed to obtain a general partition, and ensure that the models used in each zone are both efficient and economical. We use DNS results as the standard, with an error within 5% as the partition basis. According to the results, the calculation accuracy after hybridization reaches 99% of using DNS alone. Besides, the amount of calculation required is only 59% of using DNS alone, which is smaller than DNS. On this basis, we can achieve our goal based on the hybrid method. Meanwhile, it is also aware that our method is still needed to be improved, where we will gradually make this method in future work. These results shed light on a new hybrid method.