Heat Transfer in porous media

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 July 17, 2014, 06:04 Heat Transfer in porous media #1 New Member   Join Date: Jul 2014 Posts: 2 Rep Power: 0 Hi, I am trying to model a heat exchanger using porous media approach in CFX 15. In the porous domain setting, for the solid model, I would like to set the solid temperature as an expression that is temperature varying with space. When I try to do that, it gives me the following error -------------------- Parameter 'Solid Temperature' in object '/FLOW:Flow Analysis 1/DOMAIN:Core_Porous_Domain/SOLID MODELS/HEAT TRANSFER MODEL' is not allowed to be assigned an expression value that depends on variables. It must be assigned a numeric value, or an expression that resolves to a constant value. --------------------- Has anyone modeled heat transfer in porous media using CFX? It would be great if he/she can guide me doing this. Pls let me know in case you need any other info. Thanks in anticipation. Regards, Deb

 July 17, 2014, 07:20 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,480 Rep Power: 140 Please post your CEL.

July 17, 2014, 16:59
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Heat transfer between the solid matrix, and the fluid within porous media is supported since ANSYS CFX Release 13.0.

You can review the Catalytic Converter tutorial (tutorial 12) for details.

Quote:
 To model the presence of the honeycomb structure that exists in the housing, you will model porosity and apply resistance to the flow. The honeycomb structure has a porosity of 70%, which means that 70% of the total volume is available for fluid flow, while the other 30% is occupied by the solid material that comprises the honeycomb structure. The solid component of the structure will be steel. The honeycomb structure is lined up with the flow to prevent flow travel in the transverse direction. To model resistance to the flow, you will apply a streamwise quadratic resistance coefficient of 650 kg m^-4. To reduce the amount of transverse flow, apply a quadratic resistance coefficient of 6500 kg m^-4 in the transverse direction. These given resistance coefficients are based on the superficial flow velocity, rather than the true flow velocity.
The error message you are getting is because the Isothermal model assumes the temperature is not only constant in time, but uniform in space; therefore, it cannot be a field variable.

If you explain in more detail what you are trying to model in addition of how you are trying to achieve it, other members in the forum may be able to help you.