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Lagrangian approach to mesh-free modelling of two-phase vortex flowsтезисы доклада
- Авторы: Lebedeva N.A., Osiptsov A.N.
- Сборник: 10th European Fluid Mechanics Conference
- Тезисы
- Год издания: 2014
- Место издания: Technical University of Denmark Copenhagen
- Аннотация: The main goal of the study is to develop novel models and approaches for mathematical modeling of the interaction of localized vorticity zones of different kind with an inertial dispersed admixture. The method proposed is applicable to simulation of unsteady viscous flows with a dilute admixture of non-colliding particles which do not affect the carrier phase. The approach is based on a modification and combination of the full Lagrangian method1 for the dispersed phase and a Lagrangian mesh-free vortex method based on the diffusion velocity for Navier-Stokes equations describing the carrier phase2-3. In the combined numerical algorithm, both these approaches have been implemented and used at each time step. In the first stage, the vortex-blob approach is used to calculate the fields of velocity and spatial derivatives of the carrier-phase flow. In the second stage, using full Lagarngian approach, the particle velocity and number density are calculated along chosen particle pathlines. In this case, the problem of calculation of all parameters in both phases (including particle concentration) is reduced to the solution of a high-order system of ordinary differential equations, describing transient processes in both carrier and dispersed phases. Due to a very high ‘compressibility’ of dilute admixture in complex transient flows, various flow features can be manifested, e.g. discontinuities and singularities in the dispersed-phase concentration, multiple intersections of particle trajectories, formation of ‘folds’ in the particle continuum, etc. The correct simulation of these flow features involves serious difficulties when conventional Eulerian or Eulerian/Lagrangian methods, described in the literature, are used. The combined fully Lagrangian approach, proposed here, allows one to study in detail local zones of particle accumulation in transient two-phase flows with different ratios of phase material densities, including aerosol or dusty-gas flows and flows of bubbly liquids or dilute suspensions. As an example, the method is applied to simulate the development of vortex ring-like structures in an impulse two-phase jet flows. This flow involves the formation of local zones of particle accumulation, regions of multiple intersections of particle trajectories, and multi-valued particle velocity and concentration fields. The proposed combined Lagrangian mesh-free approach enables one to reproduce with controlled accuracy all these flow features without excessive computational costs.
- Добавил в систему: Лебедева Наталья Анатольевна