[iSaeed]

Hello everyone
First of all Happy christmas !!
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I wanted to know how is possible to define "brownian thermal conductivity" in star ccm with field function or user coding?
Please bear in mind that in brownian thermal conductivity definition we have a "space variable" namely "Temperature". According to Star CCM's User Guide which i'll quote it here :
"Variables such as $Temperature or $Pressure have different values at every different point in space and cannot be used in expressions". Page 5970 !!

so at first glance it seems i can't use field function to define "brownian thermal conductivity" or other parameters like this. but there should be a way to overcome this issue !!
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To be more specific i just wanted to simulate heat transfer enhancment let's say in a car radiator pipe or a heat exchanger coil pipe (just to give a clue about my simulation scale) via using nanofluid. i've done some researchs and read publications in this area and i figured out that in general we have 2 ways. (correct me if i'm wrong)
1- use a single phase media with implementing equivalent nanofluid parameter such as effective heat conductivity or density ...
very simple method
2- use multiphase model.
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As i've stated above if i want use method 1 for my simulation, i should define some UDF's (in star ccm software we call them field functions) for some parameters like "Brownian Heat Conductivity" which in it's formula we have a space variable namely "Tempearture". but since I'm using Star CCM+ software , i can't define an express which has a space variable such as Temperature or Pressure.
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and for method 2 i'm not very familiar with Multiphase models
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so :
1- in your opinion which one of mentioned methods might have better results and acuracy ?
2- what is the best multiphase model and general assumptions with given information about my goal.
3- if you have any advise, plaese don't hold back

Many Thanks
Best Regards !