Porous Media Fluent – Catalytic Converter / Packed Bed – why nitrogen?

[Jee Loong Hee]

Hello,

I am currently learning from the tutorial for Porous media before implementing the 'same' strategy for cylindrical packed bed. 

I have checked the tutorial for Porous Media and there was an example for a catalytic converter (for gas exhaust). I do not quite understand, why is the material for porous media is 'selected' as 'nitrogen' in the drop-down material menu of fluid:substrate1 and fluid:substrate:2 (in tutorial: Chapter 3: Modeling Flow Through Porous Media)?

Shouldn't that be platinum, etc? If say a metal catalyst material is selected, what would happen to the modelling result? Does it means that the inlet gas (which is nitrogen) must match the porous media (material?).

For my question no.2, I could see that for porous media, the ANSYS tutorial opt for laminar zone for the porous media, since the inlet velocity is 125 m/s, the idea of setting laminar zone is to stabilise the flow regime within the porous media (assumption) making the solver stable?

Thanks
Jee 

[Jee Loong Hee]

 

 

Oh, please forgive my silly question. I understood it now. So only in the heat transfer (energy problem) that the material of the porous media matters, which can be selected in the thermal model (in POROUS tab). 

 

 

[Rob]

Not a problem, if you don't know and then learn something it's not a silly question. The gas/liquid material is the flowing fluid (air/nitrogen/mixture) and the "solid" bit may well be platinum or wool (don't ask) should you need to account for enhanced conduction in the zone.