Multi body part and fluctuating residuals
 

Dear collegues

I am new to fluent. I have modeled a room 8m length by 4m. The room has 2 windows and 1 door on windward side and 2 windows and 1 door on leeward. I have also modeled the atmospheric air as an enclosure of the room. (Can this model be a multi body part model because the mesher is giving me a warning that this is a multi body part and hence cutcell meshing may not be appropriate). The atmospheric air enclosure measures 252m (width) by 256m (length) by 105m (height). I am using polyhedra mesh. I am running steady flow simulation. The energy equation is off. The solution has converged after 77 iterations. I am having fluctuating residuals and the continuity and epslon residuals are fluctuating above 10e-3. The others are fluctuating below. What causes these fluctuations and how can I solve the problem. May you please assist with regard to the above.

Thank you in advance for any contributions.