ball valve actuation torque estimation using CFD tool

[thought2007]

Industrial expert's opinion is maximum torque required to actuate ball valve is
"Torque ability to open under large differential pressure and to close under high flow conditions "

My objective is to determine Actuation torque Vs Pressure drop curve (through digital prototyping) using CFD analysis tool.

Design employ trunion mounted ball valve design approach and its stem are supported by bearings
Flow rate: 17.2gpm
Operating pressure: 60psi
Max pressure drop at open condition: 0.5psid

Now my question is how to built boundary conditions for CFD analysis and I carried out using following conditions in flow model to determine pressure drop for various opening angles but results are varying drastically

Upstream condition
17.2gpm Downstream condition
60psi Unknown

Would request you all is this right method to analyze
1. How ball valve is testing is done on test bench to
determine Torque Vs Pressure drop
2. Do I need to give Pressure drop 0.5psi at downstream
conditions as this requirement when ball is open
conditions than analyze pressure drop for various
opening angles
3. Do i need to give Upstream conditions as 60psi and
downstream conditions as Flow rate 17.2gpm than analyze
pressure drop for various opening angles

Your suggestions are well appreciated

Thanks & regards
John