Different SGS models in large eddy simulation of 90° square cross-section bends

Abstract

The turbulent flow inside a 90° bend with a square cross section is investigated numerically. The flow field is simulated using the large eddy simulation (LES) technique with different subgrid scale (SGS) models. The simulations are performed for two moderate and high Reynolds numbers of 10⁴ and 10⁵. The details of flow field are compared with predictions of one type of Reynolds stress models (RSM), i.e. Launder-Reece-Rodi model and the available experimental data. Among the studied SGS models, the appropriate form for the LES technique at the bend flow is introduced. The results of LES are in a better agreement with the experimental data compared with the RSM for mean and fluctuating velocities. LES also presents a better perdition for transverse velocities in the bend sections. Moreover, some additional secondary flow vortices are captured by LES.

Keywords:

• large eddy simulation
• SGS model
• bend
• coherent vortices