Temperature stratification simulation in CFX
 

Hello,

I'm modeling a reservoir with temperature stratification and to see temperature change with cold inflow.

Firstly, I set the reservoir has only one temperature (25 C), so the density in the reservoir is also constant (997 kg/m^3), Buoyancy Reference Temperature is 25 C， inflow is 4 C with speed of 2m/s. The result is not bad, we can see the cold water plunge in to the reservoir, show in the first picture.

Secondly, I set the reservoir has two layers with different temperature (25 C and 4 C), and the density in different layers is 997 kg/m^3 and 1000 kg/m^3 respectively, Buoyancy Reference Density is 997 kg/m^3， inflow is 4 C with speed of 2m/s. Here I change the material option (only change the density distribution). The result is terrible, we cannot see any plunging in to the reservoir, show in the second picture.

I'm sure the boundary condition (pressure) is no problem, but I'm wandering the problem is in Material Setting (only change Density)? I keep material group to be Water Data, Constant Property Liquids. Is that all right? Need I change Reference State (Reference temperature & Pressure)?

Thank you in advance!
Marble