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Rebecca April 23, 2009 10:24

Number density tracking rather than particle tracking
 
I am searching for evidence that a CFD method exists and is tested involving population density tracking rather than tracking of individual particles. I have yet to find a key phrase that will give me the method I describe in my literature search. Here is an indication of the types of flow I am considering:
air
multiple types of particles: water insoluble, water soluble, different diameters

the flow will be moist, so water droplets will be forming in the flow, on aerosols, and will be changing particles to translucent

Ideally, I will be able to follow all of this. Tracking each particle through this flow seems insane to me. I want to implement a method by which I track the population density of each type of particle, noting in which area of the mesh they change from one type to another (particle without water on it to a particle with water on it, eg.), based on the conditions and the probability that a particle would undergo such a phase change (if there is a 35% chance that one particle would do it, then 35% of the particles in the cell do it). Anyone heard of this? My advisor says he hasn't. Scientific papers or a name for this methodology will be very useful. Please email me with your answer.

Thank you so much.

silva April 23, 2009 11:58

Hi Rebecca,

You are looking for the multivariate population balance modelling approach where the particle-particle interactions may affect the flow patterns. Thus, the particle interactions, such as breakage, aggregation, growth, nucleation, should be included in the polydisperse multiphase flow simulations through the population balance equation [1] and the Eulerian multi-fluid model [2,3] coupling. You should take a look about this.

The Direct Quadrature Method Of Moments (DQMOM) [4] would be the best choice for the solution of the population balance. It can be used to obtain the moments of the property distribution function, including the zero moment (number of particles), first moment (mass) and combined moments can provide the mean Sauter diameter, for instance.

Hope I helped a little bit :). Take a look at the references below.

Best regards,
Luiz F.

References:
[1] Ramkrishna, D. Population Balances Theory and Applications to Particulate Systems in Engineering. Academic Press, New York, 2000.
[2] Ishii, M., Hibiki, T., Thermo-Fluid Dynamics of Two-Phase Flow. 1st ed. Springer: Nova York, EUA, 2006.
[3] Enwald, H., Peirano, E., Almstedt, A.-E., Eulerian two-phase flow theory applied to fluidization, International Journal of Multiphase Flow, v. 22, n. Supp. 1, pp. 21-66, 1996.
[4] Marchisio, D.L. and Fox, R.O. Solution of the population balance equation using the direct quadrature method of moments. Journal of Aeorosol Science, Volume 36, 43-73, 2005.

Rebecca April 23, 2009 12:52

Thank you, Luiz.
These terms and references are very helpful! I think I have what I need to justify this method and references to make sure I do it correctly. I appreciate your advice.


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