Comparative computational study of turbulent flow in a 90° pipe elbow

• The significantly complex flow through a pipe bend is computed and analyzed for various Reynolds numbers.
• Different state-of-the-art methods are employed and compared to one another.
• The results are successfully validated against experimentally obtained data where available.
• A comparative assessment of relevant mean flow quantities is performed.
• Turbulence structures are identified in detail and characterized accordingly.

Turbulent flow through a 90°90° pipe elbow in a range of moderately high Reynolds numbers between 14,000 and 34,000 is studied computationally using wall-resolved large-eddy simulation (LES) as well as various RANS (Reynolds-averaged Navier–Stokes) models aiming at a comparative assessment to illustrate benefits and drawbacks of different computational approaches for the considered case. The RANS models applied in the framework of this study include both the basic low Reynolds number k  –εε-model, see Launder and Sharma (1974), as well as a near-wall second moment closure model as proposed by Jakirlić and Maduta (2015). Accordingly, the respective results for the mean flow fields being subjected to strong pressure variations – thus causing locally alternating flow acceleration and deceleration which are correspondingly reflected in a distinct Reynolds stress anisotropy variability – are analyzed in detail along with experimental data by Kalpakli and Örlü (2013). Furthermore, characteristic secondary motions resembling the axially oriented counter-rotating Dean vortices, see Bradshaw (1987), are further investigated and their predictability using LES is assessed.