KNOWN ISSUE: High Speed Wall Functions produce poor results for Low Speed flow (Class 3 Error)
The CFX-Solver may experience robustness problems, and produce overshoots and undershoots in the temperature solution at walls, when the viscous work term is enabled for low speed flows.
High speed wall functions are activated by default for compressible fluids when the viscous work model is activated together with the total energy model. However, these wall functions are do not perform well for low speed flows. Under low speed conditions one should disable the high speed wall functions by using the CCL parameter High Speed Model = Off. However, a bug in the CFX-Solver prevents this parameter having any effect.
No workaround is currently available.
ANSYS CFX Release 12.1. A custom executable for ANSYS CFX Release 12.0 is available on request.