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A massively parallel hybrid scheme for direct numerical simulation of turbulent viscoelastic channel flow

type de publication      article dans une revue internationale avec comité de lecture
date de publication 2011
auteur(s) Thais Laurent; Tejada-Matinez Andrés E.; Gatski Thomas B.; Mompean Gilmar
journal (abréviation) Computers & Fluids (Comput Fluid)
volume (numéro) 43 (1)
pages 134 – 142
résumé This paper describes in detail a numerical scheme designed for direct numerical simulation (DNS) of turbulent drag reduction. The hybrid spatial scheme includes Fourier spectral accuracy in two directions and 6th-order compact finite differences for first and second-order wall-normal derivatives, while time marching can be up to 4-th order accurate. High-resolution and high-drag reduction viscoelastic DNS are made possible through domain decomposition with a two-dimensional MPI Cartesian grid alternatively splitting two directions of space (’pencil’ decomposition). The resulting algorithm has been shown to scale properly up to 16384 cores on the Blue Gene/P at IDRIS-CNRS, France. Drag reduction is modeled for the three-dimensional wall-bounded channel flow of a FENE-P dilute polymer solution which mimics injection of heavy-weight flexible polymers in a Newtonian solvent. We present results for 4 high-drag reduction viscoelastic flows with friction Reynolds numbers Reτ0=180, 395, 590 and 1000, all of them sharing the same friction Weissenberg number Weτ0=115 and the same rheological parameters. A primary analysis of the DNS database indicates that turbulence modification by the presence of polymers is Reynolds-number dependent. This translates into a smaller percent drag reduction with increasing Reynolds number, from 64% at Reτ0=180 down to 59% at Reτ0=1000, and a steeper mean current at small Reynolds number. The Reynolds number dependence is also visible in second-order statistics and in the vortex structures visualized with iso-surfaces of the Q-criterion.
mots clés Parallel algorithm; Drag reduction; Polymer; Turbulence; DNS; Channel Flow
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