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-   -   Influence of particle diameter in multi-phase flows? (http://www.cfd-online.com/Forums/openfoam-solving/109297-influence-particle-diameter-multi-phase-flows.html)

petr.f. November 14, 2012 11:04

Influence of particle diameter in multi-phase flows?
 
Hi all,

considering the multi-phase solvers (multiphaseEulerFoam, twoPhaseEulerFoam) - what is the particle diameter influence on computation? It must be set for both liquid and gas phases so are there any hints how to determine it e.g. for water and air? Should it be greater or smaller than the smallest cell in computational mesh?

Any help appreciated...

GerhardHolzinger January 31, 2013 07:37

The Eulerian solvers are used to simulate a dispersed phase (dust, droplets, etc.) and a continuos phase (air, water). Both phase can take the whole domain (e.g. foggy air). Instead of filling a control volume (a cell) completely with one phase, both phases use up this volume up to a certain fraction. The sum of this volume fractions must be one.

A half empty glass of water is filled by 50 % with water and the rest is air. The Eulerian solvers work in a similar way. the volume fraction of the dispersed phase tells you whether a cell is filled with one phase, the other phase or a mixture of both phases.

The momentum exchange terms depend on the particle diameter. If you use a blended drag model, both diameters are used. If you specify a drag phase, the diameter of the continuous phase should be of no importance.

The diameter of the dispersed phase should be set according to your problem in mind, e.g. for air bubbles in water, you should use the bubble diameter.

sharonyue April 8, 2013 03:56

Quote:

Originally Posted by GerhardHolzinger (Post 405266)
The Eulerian solvers are used to simulate a dispersed phase (dust, droplets, etc.) and a continuos phase (air, water). Both phase can take the whole domain (e.g. foggy air). Instead of filling a control volume (a cell) completely with one phase, both phases use up this volume up to a certain fraction. The sum of this volume fractions must be one.

A half empty glass of water is filled by 50 % with water and the rest is air. The Eulerian solvers work in a similar way. the volume fraction of the dispersed phase tells you whether a cell is filled with one phase, the other phase or a mixture of both phases.

The momentum exchange terms depend on the particle diameter. If you use a blended drag model, both diameters are used. If you specify a drag phase, the diameter of the continuous phase should be of no importance.

The diameter of the dispersed phase should be set according to your problem in mind, e.g. for air bubbles in water, you should use the bubble diameter.

Hi,

Long time no see~Have you ever test twophaseeulerfoam on a tet mesh? How is the result?


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