[Kiat110616]

Dear All,


I'm a little confused about different domain condition.
First case study, I created the only one fluid model.


Domain Settings
- Domain Type @ Fluid domain
- Reference pressure @ 1 atm
- Domain motion @ stationary
- Mesh Deformation @ regions of motion specified

Boundary Condition
- Total pressure at an inlet surface
- Mass flow rate at an outlet surface
- Runner surface is set up with a angular velocity
- Other surface is set up to stationary wall (no slip wall)


CFX Post-One domain.jpg


Second case study, I created the two fluid models. I have separated the model into two domains is stationary and rotating domain.


First domain settings
- Domain Type @ Fluid domain
- Reference pressure @ 1 atm
- Domain motion @ stationary


Second domain settings
- Domain Type @ Fluid domain
- Reference pressure @ 1 atm
- Domain motion @ rotating along Z axis


Interface settings
- Interface models @ general connection
- Frame change @ Frozen rotor
- Pitch change @ none


Boundary Condition
- Total pressure at an inlet surface @ stationary domain
- Mass flow rate at an outlet surface @ rotating domain
- Other surface is set up to wall condition (no slip wall)


CFX Post-Two domain.jpg


The results of both case studies are different. The total pressure different between inlet and outlet of the first case is 71 kPa and second case is 54 kPa. Also, the hydraulic efficiency of both case studies is different. It is important to determine which case study is accurate. Any feedback is greatly appreciated.