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Old   May 14, 2012, 08:38
Default packed-bed geometry creation
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sara
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dear all
I'm trying to do some analysis on latent heat thermal energy storage using a packed bed of spheres, i need to run the simulation in 2d but the problem is that the direct treatment as a 2-D model will lead to no flow passage for the fluid due to the complex packing of the spheres and the contact between them.
the bed have following dimensions:
360mm diameter
460mm height
264 spheres with outer diameter of 55mm uniformly packed in eight layer

anyone can help with this?
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Old   May 14, 2012, 12:49
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if you are using Fluent (I just know Fluent has a porous media model) you can treat it as porous media. You'll have to figure out some of the variables, but it can be done. There are journal articles written modeling it as porous media too.
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Old   May 15, 2012, 06:09
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Quote:
Originally Posted by mettler View Post
if you are using Fluent (I just know Fluent has a porous media model) you can treat it as porous media. You'll have to figure out some of the variables, but it can be done. There are journal articles written modeling it as porous media too.
thnx for the response mettler
do you have any specific article in mind to help me with this?
i also wanna treat it as a porous media but i have problem with the geometry, i don't know how i should put the spheres so that have acceptable flow passage. by the way the void fraction or the bed porosity is 0.48.
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Old   May 15, 2012, 08:47
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If you are using Fluent you will not have to draw every sphere etc. You will just have to draw the dimensions of the pipe/bed/whatever that is holding the spheres and then define certain variables that will let Fluent know that the section is a packed bed. The porosity will be one of them. When I did this a few years ago I had to do some measurements in the lab to get some of the other variables. Fluent's manual has a good section on porous media that will help you understand it better.

I'll try to remember to get some author's names when I get home. Jiang comes to mind, but I am not sure if it was packed beds he was doing.
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Old   May 15, 2012, 15:20
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I'm using ansys fluent 13
I need the liquid fraction of the pcm (phase change material which is paraffin wax ) and the outlet temperature after the system is being totally charged...

so you sure that i don't have to draw every sphere?
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Old   May 15, 2012, 15:31
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get out the fluent PDF and read the porous media section.. yes, you don not have to draw all the spheres..

You will separate you section into an entrance length, and then the fluidized bed, and an exit section. The bed section will be defined as porous media and you will have to fill in all the necessary variables. That is what I had to do anyway.
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Old   May 15, 2012, 15:56
Default Rheolef NEW version 6.1: an efficient FEM C++ finite element library for solving PDE
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Pierre Saramito
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Rheolef: an efficient FEM C++ finite element library for solving PDE

Version : 6.1
Book: http://ljk.imag.fr/membres/Pierre.Sa...ef/rheolef.pdf
Home: http://ljk.imag.fr/membres/Pierre.Saramito/rheolef

Distibution: sources and binaries as debian packages

Keywords: finite elements, numerical simulation, partial derivative equations,
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Pierre Saramito
--
Pierre.Saramito@imag.fr
Directeur de Recherche CNRS
Laboratoire Jean Kuntzmann, Grenoble, France
http://www-ljk.imag.fr/membres/Pierre.Saramito
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Old   May 16, 2012, 23:53
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thnx mettler it was helpfull
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Old   May 20, 2012, 18:24
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Sara:

I'm aware of 2 similar things that we've done. The first is written about on our website:

http://www.pointwise.com/theconnecto...edia-CFD.shtml

In another case we scripted the meshing of the flow around an automatically generated array of a variety of sphere sizes. We can't show pictures of that because it was proprietary to the client. But we could describe how it was meshed.

If interested in the details, send me an email at jrc@pointwise.com and I'll forward it to the right people who can give you the answer.

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