Rob
Ansys Employee

Right, so it's not perturbed, you're running a swirling flow.  If the original case didn't have swirl check the cell zone settings to ensure you're actually swirling about the correct axis. Why do you need to include temperature, looking through you've not mentioned any heat transfer: 40m/s is well below 0.3M so the solution may not be overly compressible. I'd also look at the back flow conditions, and extend the domain so the back flow isn't influencing the system.