title: Rotation of Nonspherical Particles in Turbulent Channel Flow.
abstract: The effects of particle inertia, particle shape, and fluid shear on particle rotation are examined using direct numerical simulation of turbulent channel flow. Particles at the channel center (nearly isotropic turbulence) and near the wall (highly sheared flow) show different rotation patterns and surprisingly different effects of particle inertia. Oblate particles at the center tend to rotate orthogonally to their symmetry axes, whereas prolate particles rotate around their symmetry axes. This trend is weakened by increasing inertia so that highly inertial oblate spheroids rotate nearly isotropically about their principle axes at the channel center. Near the walls, inertia does not move the rotation of spheroids towards isotropy but, rather, reverses the trend, causing oblate spheroids to rotate strongly about their symmetry axes and prolate spheroids to rotate normal to their symmetry axes. The observed phenomena are mostly ascribed to preferential orientations of the spheroids.
authors.affiliation: Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Lihao
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Niranjan Reddy
authors.initials: NR
authors.lastname: Challabotla
authors.affiliation: Department of Energy and Process Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Helge I
authors.initials: HI
authors.lastname: Andersson
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, USA.
authors.forename: Evan A
authors.initials: EA
authors.lastname: Variano