Meaning of Pressure Work and Viscous Work

[rademacherdacostacabral.v]

I have a simulation of an open volume of air with a fan inside. I want to examine (among other things) how much heat the fan would introduce to my system if it were closed (the real system I simulate is a closed volume of air).

I have read the documentation and understood that there is pressure and viscous work and to my understanding both would dissipate to heat in a closed system? Now If I evaluate pressure and viscous work at the wall of my fan, it returns a combined power of 6 W. Is this the total dissipated power? Or do I have to take other factors into account such as the kinetic energy of the fluid exiting my system? I understand this is less a question regarding fluent but somewhat a question regarding fluiddynamics in general.

Help is much appreciated!
Kind regards
Vincent

[rfblumen]

Consider the efficiency of the fan, which is defined as the ratio of the useful work on the fluid (i.e. the increase in the mechanical energy stored in the fluid) to the shaft work.  The shaft work represents the product of the torque on the fan blade times the angular velocity.  The torque includes contributions from both the pressure force on the blade and the force from wall shear stress on the blade.  If it's assumed that the useful work on the fluid is not dissipated as heat, the total dissipated power would then be based on the difference in the shaft work and the useful work.  If one assumes that all the useful work is dissipated as heat, then the total dissipated power would be based on the shaft work.  These two assumptions bound the total dissipated power which would manifest as a temperature increase.