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Turbulent pipe flow: New DNS data and large-scale structures

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Large-scale fully resolved direct numerical simulations (DNSs) have been performed with a high-order spectral element method to study the flow of an incompressible viscous fluid in a smooth circular pipe of radius R and axial length 25R in the turbulent flow regime at four different friction Reynolds numbers Reτ = 180, 360, 550 and 1000. The new data is compared to other simulation data sets, obtained in pipe, channel and boundary-layer geometry. The pressure is the variable that differs the most between the cases; a significantly higher mean and fluctuating pressure are observed in boundary layers that is linked to a stronger wake region. Critical assessment of the available DNS data is conducted in order to determine which difference or correspondence between the data sets are real and caused by physics, and which discrepancies are likely due to statistical or numerical inaccuracies. Furthermore, two- dimensional spectra of axial/streamwise velocity show an imprint of the large-scale motions from the outer layer in all canonical flows, however with different amplitude.

Author(s):

George El Khoury    
Linné FLOW Centre, KTH Mechanics, Royal Institute of Technology, Stockholm, Sweden
Sweden

Philipp Schlatter    
Linné FLOW Centre, KTH Mechanics, Royal Institute of Technology, Stockholm, Sweden
Sweden

Geert Brethouwer    
Linné FLOW Centre, KTH Mechanics, Royal Institute of Technology, Stockholm, Sweden
Sweden

Arne V. Johansson    
Linné FLOW Centre, KTH Mechanics, Royal Institute of Technology, Stockholm, Sweden
Sweden