Suitable Boundary Condition

Hi,

 

I'm working on a radiator fan analysis. I have the experimented flow parameters such as pressure, air flow rate and speed of the fan. 

 

I have solved two different cases with boundary conditions as below

 

1. Defined Flow rate at the inlet and speed of the fan using MRF method. (Validating Pressure Drop)

2. Defined Pressure drop value at the inlet and speed of the fan using MRF method. (Validating Flow Rate)

 

It looks both the cases while defining boundary conditions is same but they vary widely in their result.

 

Please suggest the suitable method of defining the boundary condition for this case with valid reason.

 

Regards,

Vignesh V.