Which multiphase flow to solve this problem?
 

Hello I am tried to solve nanofluid problem with base fluid water and Al2O3 as particles flowing into a pipe I want to predict heat transfer coefficient and temperature distribution at the pipe wall which multiphase flow model is better to solve my problem?

I think your problem is not difficult to resolve!! Choose a eulerian model and set the second fluid as a granular!!!

Thanks a lot Costa for the answer. I need to ask I have solid particles of Al2O3 can fluent treat it as another phase? I took your advise about granular it need the granular viscosity the default value is 1e-05 and granular bulk viscosity (which i do not know?) how much i set its value?

Yes Al2O3 will be treat as another phase. You have in fluent two model for modeling dispersed solids particles:
1ª Eulerian model (granular)
2ª Mixture model (granular)
If you have much interation (contact) between the solid particles and the volume fraction is high i dont remeber but i think the Eurelian is more apropriate. In another case use Mixture model. Look this paper:
http://mech.vub.ac.be/thermodynamics...ryk_Widera.pdf