packed-bed geometry creation

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 May 14, 2012, 08:38 packed-bed geometry creation #1 New Member   sara Join Date: May 2012 Posts: 5 Rep Power: 5 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?

 May 14, 2012, 12:49 #2 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 194 Rep Power: 8 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.

May 15, 2012, 06:09
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sara
Join Date: May 2012
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Quote:
 Originally Posted by mettler 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.

 May 15, 2012, 08:47 #4 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 194 Rep Power: 8 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.

 May 15, 2012, 15:20 #5 New Member   sara Join Date: May 2012 Posts: 5 Rep Power: 5 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?

 May 15, 2012, 15:31 #6 Senior Member   Andrew Join Date: Mar 2009 Location: Washington, DC Posts: 194 Rep Power: 8 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.

 May 15, 2012, 15:56 Rheolef NEW version 6.1: an efficient FEM C++ finite element library for solving PDE #7 New Member   Pierre Saramito Join Date: Oct 2009 Location: Grenoble, France Posts: 6 Rep Power: 7 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, C++, meshes, graphics News: * equations on a surface: implements three diferent FEM methods * improves the high order Pk Lagrange interpolation implementation * ports on intel c++ 12.0 and gnu c++ 4.7 new compiler versions Previous features: Rheolef is a programming environment that serves as a convenient laboratory for computations involving finite element methods (FEM) for solving partial differential equations (PDE). Rheolef is both a C++ library and a set of commands for unix shell programming, providing algorithms and data structures. * Algorithms refer to the most up-to-date ones: preconditioned sparse solvers for linear systems, incompressible elasticity, Stokes and Navier-Stokes flows, characteristic method for convection dominated heat problems, etc. Also nonlinear generic algorithms such as fixed point and damped Newton methods. * Data structures fit the standard variational formulation concept: spaces, discrete fields, bilinear forms are C++ types for variables, that can be combined in any expressions, as you write it on the paper. Combined together, as a Lego game, these bricks allows the user to solve most complex nonlinear problems. The concision and readability of codes written with Rheolef is certainly a major keypoint of this environment. Main features * [NEW] Massively distributed memory finite element environment, based on MPI. * [NEW] High-order polynomial approximation. * Poisson problems in dimension d=1,2,3. * Stokes problems (d=2,3), with Taylor-Hood or stabilized P1 bubble-P1 elements. * linear elasticity (d=1,2,3), including the incompressible case. * characteristic method for time-dependent problems: transport, convection-difusion, and Navier-Stokes equations. * input and output in various file format for meshes generators and numerical data visualization systems. Advanced features * auto-adaptive mesh algorithms. * axisymetric problems. * multi-regions and non-constant coefficients. * nonlinear problems with either fixed-point algorithms or a provided generic damped Newton solver. * 3d stereo visualization Both reference manual and users guide are available. The license is GPL. Pierre Saramito -- Pierre.Saramito@imag.fr Directeur de Recherche CNRS Laboratoire Jean Kuntzmann, Grenoble, France http://www-ljk.imag.fr/membres/Pierre.Saramito

 May 16, 2012, 23:53 #8 New Member   sara Join Date: May 2012 Posts: 5 Rep Power: 5 thnx mettler it was helpfull

 May 20, 2012, 18:24 #9 Senior Member   John Chawner Join Date: Mar 2009 Location: Fort Worth, Texas, USA Posts: 221 Rep Power: 9 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. Best Regards __________________ John Chawner / jrc@pointwise.com / www.pointwise.com Blog: http://blog.pointwise.com/ on Twitter: @jchawner

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