Thanks for commenting,nI want to clear here one thing that inside the fluid region solid(rotor) is also rotating I just want to determine heat transfer from the rotor to the casing. Am I making it different than what I am thinking to simulate by providing motion to the solid rotor and fluid region? basically, I have to rotate the heated rotor dissipating heat to surrounding air, and enhancing its turbulence will increase heat transfer to the casing practically. Also please note that there is no inlet and outlet for air as it is trapped in the casing.nI have attached the error message when I check for the case.nFor this error respective description inside Ansys docs, I have referred but still not clear. even though manually setting nRotor- solid motion nRotating fluid- frame motionn(moving walls between the solid casing and rotating fluid ) n(stationary wall between the rotor and rotating fluid).nnReally grateful for your help. you are doing a wonderful job here helping othersnYogeshnn