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-   -   Solid Properties Setup In Simulation of Porous Media (http://www.cfd-online.com/Forums/fluent/98914-solid-properties-setup-simulation-porous-media.html)

Modest Cat March 21, 2012 21:54

Solid Properties Setup In Simulation of Porous Media
 
Hi guys~

In order to simulate heat transfer between gas and solid in porous media, I add an additional UDS which represents the solid energy equation. Meanwhile, I still want to use the porous media(PM) energy equation given by FLUENT to calculate the heat transport in gas. So I have to remove all solid items in PM equation by setting all solid properties (Cp\density\conductivity) ZERO!!!

Is this the right way to build the double energy equation model?:confused:

Regards

LuckyTran March 24, 2012 01:22

Quote:

Originally Posted by Modest Cat (Post 350785)
Hi guys~

In order to simulate heat transfer between gas and solid in porous media, I add an additional UDS which represents the solid energy equation. Meanwhile, I still want to use the porous media(PM) energy equation given by FLUENT to calculate the heat transport in gas. So I have to remove all solid items in PM equation by setting all solid properties (Cp\density\conductivity) ZERO!!!

Is this the right way to build the double energy equation model?:confused:

Regards

The Porous Media energy equation already accounts for thermal transport due to both solid and gas. You do not need to do anything. The effective thermal conductivity of the porous section is calculated with a weighted average of the solid/fluid contributions (through porosity).

Don't forget that in addition to the material properties, you also need to specify the porosity! If you want to calculate heat transport only due to gas, an even easier method is to set the porosity to 0. porosity = 1 will give you the opposite extreme. But changing the porosity will also change the way the momentum is dealt with, so this is probably not what you want to do in this case.

Modest Cat March 26, 2012 03:20

Quote:

Originally Posted by LuckyTran (Post 351202)
The Porous Media energy equation already accounts for thermal transport due to both solid and gas. You do not need to do anything. The effective thermal conductivity of the porous section is calculated with a weighted average of the solid/fluid contributions (through porosity).

Don't forget that in addition to the material properties, you also need to specify the porosity! If you want to calculate heat transport only due to gas, an even easier method is to set the porosity to 0. porosity = 1 will give you the opposite extreme. But changing the porosity will also change the way the momentum is dealt with, so this is probably not what you want to do in this case.

Dear LuckyTran,

Thanks for your reply. I think I completely understand your words. But one assumption that FLUENT make is thermal equilibrium between gas and solid, and this is not the situation of mine, which contains combustion and sufficient convection heat transfer in the model.

So, when I use the equation which FLUENT has to solve the gas energy equation (only), I can set the porosity 0. However, with this, I cannot using the physical velocity, as you said.

What I want to do is keep the porosity (like 0.39), and at the same time, remove the influence of solid, just like setting porosity 0.

I just don't know what I've done is reasonable or not (-by setting all solid properties 0).

I hope I've express my thought clearly.

Kind regards,
Samuel

LuckyTran March 26, 2012 03:37

Quote:

Originally Posted by Modest Cat (Post 351424)
Dear LuckyTran,

Thanks for your reply. I think I completely understand your words. But one assumption that FLUENT make is thermal equilibrium between gas and solid, and this is not the situation of mine, which contains combustion and sufficient convection heat transfer in the model.

So, when I use the equation which FLUENT has to solve the gas energy equation (only), I can set the porosity 0. However, with this, I cannot using the physical velocity, as you said.

What I want to do is keep the porosity (like 0.39), and at the same time, remove the influence of solid, just like setting porosity 0.

I just don't know what I've done is reasonable or not (-by setting all solid properties 0).

I hope I've express my thought clearly.

Kind regards,
Samuel

I understand now what you are trying to do. It should be fine if your UDS/UDF is set up properly. The solid properties should not appear anywhere else to mess up anything. I also believe your approach is correct. Again, just make sure the UDS and any UDF's are doing their job!

Modest Cat March 26, 2012 05:00

Quote:

Originally Posted by LuckyTran (Post 351430)
I understand now what you are trying to do. It should be fine if your UDS/UDF is set up properly. The solid properties should not appear anywhere else to mess up anything. I also believe your approach is correct. Again, just make sure the UDS and any UDF's are doing their job!

:) Thanks again~


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