I had created a convoluted air flow path through a duct and got good results but when I try to introduce compressibility the operation fails after a while stating;

Warning:
volume [www.10745.5] RANS Flow: Failed
Unexpected process exit.
[5]
[5]
[5] --> FOAM FATAL ERROR:
[5] Maximum number of iterations exceeded
[5]
[5] From function thermo::T(scalar f, scalar T0, scalar (thermo::*F)(const scalar) const, scalar (thermo::*dFdT)(const scalar) const, scalar (thermo::*limit)(const scalar) const) const
[5] in file /home/rjs/projects/of/2.2/OpenFOAM-2.2.x/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 76.
[5]
FOAM parallel run aborting
[5]

I left all options as is but I am sure I need to adjust something to make compressible gas work.

Thanks

Ken