Author(s): Sebastian Roger
Linked Author(s):
Keywords: Multiphase flow; Two-phase flow; Euler-Lagrange; Bubbles; Particles
Abstract: Numerical computations of two-phase flows may be performed in different ways related to the specific physical properties in the flow field under consideration. Depending on the volume fraction of the involved phases and their state of aggregation, the character of the flow differs significantly. A classification scheme for two-phase flows is introduced applying the proposed criteria on dilute, dispersed two-phase flows without phase transition. Two practical test cases, namely the particle dispersion in a single-sided backward-facing step flow and the bubbly flow over a bottom-fixed sill in a cavitation channel are examined. The air-solid stepflow has a classical setup (geometry and boundary conditions) that is often used to verify numerical approaches in fluid mechanics. The liquid-gas flow provides a completely different configuration additionally featuring the phenomenon of cavitation. Numerical simulations of the flow are performed with the EULER-LAGRANGE approach which is already implemented into the Finite Volume code of the commercial software package COMET (Version 2. 00, ICCM GmbH, Hamburg). A comparison of the numerical results with experimental data and other computations show that COMET is able to accurately model dilute particulate flows, if the particle size is calibrated. However the calculation of the bubbly flow does not yield satisfactory results because essential mechanisms like certain aspects of phase-interaction, two-phase turbulence and microscopic processes are neglected.
Year: 2005