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Porous Monolith in a pipe

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Dear All,

i'm studying heat transfer in a pipe where there is a SiC monolith surrounded by an insulating mat (see screenshot).

Up to now I have studied the system considering the monolith as pure solid using for my model only the Conjugate Heat Transfer physics.

Do I have to change physics to consider the monolith as porous?
If yes how have I to set the domain in the new physics?

Thank you in advance for your reply!
Have a nice day.


2 Replies Last Post 08.05.2013, 07:07 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 08.05.2013, 01:28 GMT-4
Hi

"My way", last year when I was studying a heat exchanger (cylinder with many >3000 pipe holes) was to estimate a "standard, small pipe based on hole ratio, total surface ratio, and surface/ volume ratios such that I made a simple 1 pipe 2D-axi model with just enough material to say it was 1/(n*1000) holes of my system.
I then studies the conjugated heat flow carefully in this simple pipe/tube 2D-axi model, it takes only a few minutes to solve so you can train well and add any type of particular in/out flow pattern and time to stabilise.

I then made a bulk model of the hole in 3D, added n*100 times my 2D-axi model as lumped parameters and solved the complex 3D system without going into the details of the n*1000 individual tubes

now if your tube bulk part is rather porous (randomly) and not anisotropic as a sieve you could consider the porous flow case, but that's a combination I haven't tried so far

--
Good luck
Ivar
Hi "My way", last year when I was studying a heat exchanger (cylinder with many >3000 pipe holes) was to estimate a "standard, small pipe based on hole ratio, total surface ratio, and surface/ volume ratios such that I made a simple 1 pipe 2D-axi model with just enough material to say it was 1/(n*1000) holes of my system. I then studies the conjugated heat flow carefully in this simple pipe/tube 2D-axi model, it takes only a few minutes to solve so you can train well and add any type of particular in/out flow pattern and time to stabilise. I then made a bulk model of the hole in 3D, added n*100 times my 2D-axi model as lumped parameters and solved the complex 3D system without going into the details of the n*1000 individual tubes now if your tube bulk part is rather porous (randomly) and not anisotropic as a sieve you could consider the porous flow case, but that's a combination I haven't tried so far -- Good luck Ivar

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Posted: 1 decade ago 08.05.2013, 07:07 GMT-4
I'm trying to use the Darcy or Brinkman equations to simulate the flow through my porous monolith, but I haven't fully understood how these physics work.

First of all I don't know how to say that in one domain (see image) there are 2 different materials. This domain is the porous solid of SiC.
I want to simulate the air passing first in the pipe and later both in the free channels and in the porosity of the solid.

Thank you for your reply.
I'm trying to use the Darcy or Brinkman equations to simulate the flow through my porous monolith, but I haven't fully understood how these physics work. First of all I don't know how to say that in one domain (see image) there are 2 different materials. This domain is the porous solid of SiC. I want to simulate the air passing first in the pipe and later both in the free channels and in the porosity of the solid. Thank you for your reply.

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