DOI: 10.1615/TSFP2
EQUILIBRIUM PUFFS DO INDEED EXIST: ACCURATE DESCRIPTION BY MEANS OF LONG-WAVE NAVIER-STOKES SOLUTIONS
RÉSUMÉ
The possibility of intermittent turbulent shear flows description by means of nonstationary long-wave 3D Navier-Stokes solutions is shown in principle. The classical problem of viscous incompressible fluid flows in a circular pipe at transitional Reynolds numbers 1800 ≤ Re ≤ 4000 is taken as a model one. By means of direct numerical simulation we have obtained statistically stationary Navier-Stokes solutions which describe turbulent (at 2500 ≤ Re ≤ 4000), intermittent (at Re = 2200, 2350) and laminar (Re ≤ 2000) flow regimes. Numerical solutions at Re = 2200,2350 describe equilibrium self-sustained flow regimes in which turbulent structures surrounded by almost laminar flow propagate downstream while preserving their length. Thus, theoretical confirmation of the existence of particular transitional flow regimes − so-called equilibrium puffs − is obtained.