Particle Reynolds number effects on settling ellipsoids in isotropic turbulence. (June 2021)

• Record Type: Journal Article
• Authors: Fröhlich, Konstantin; Farmand, Pooria; Pitsch, Heinz; Meinke, Matthias; Schröder, Wolfgang
• Is Part Of: International journal of multiphase flow. Volume 139(2021)
• Publication Date: 2021-06
• Subjects: Non-spherical particles -- Turbulent flow -- Euler-Lagrange model -- Gas-solid suspension; Multiphase flow -- Periodicals; Écoulement polyphasique -- Périodiques; Multiphase flow; Periodicals; 620.1064
• DOI: 10.1016/j.ijmultiphaseflow.2021.103566
• Languages: English
• ISSNs: 0301-9322

Abstract

Highlights: Novel ellipsoidal Lagrangian model based on recently developed drag correlations. Settling dynamics of the particles are dominated by fluid inertia corrections. Correlations are important even for moderate mean particle Reynolds numbers R e p ≤ 4 . Graphical abstract: Abstract: Recently developed drag correlations for ellipsoidal particles are applied in a Lagrangian point-particle model. The results are directly compared against a popular Lagrangian model based on the dynamic equations valid for Stokes flow for the canonical case of settling ellipsoids in isotropic decaying turbulence. For increasing terminal velocities, the pitching torque due to fluid inertia dominates the torque contribution due to the fluid velocity gradient. Consequently, the major axis is preferentially oriented perpendicular to the settling direction. The opposite is predicted, if the new correlations for ellipsoidal particles are not included in the Lagrangian model. The combined effect of the pitching torque and the drag correlations leads to significantly different settling velocities for the varying correlations. The results based on a constant particle relaxation time for various particle diameters show that the particle Reynolds number is a relevant parameter in a multiphase system even for relatively moderate particle Reynolds numbers R e p ≤ 4 .