Just went through all the conversation and i would like to share some points to check on set up .
You are getting errors such as fatal overflow in linear solver or Overflow error even notification of max mach number going too high . These all errors can be generated due to
a) improper initialization (Kindly check the reference pressure values in domain settings - units we are using ) - this may lead to unrealistic values of mass flow and properties in first few iterations only . Check if we need to provide domain initialization values of pressure .
b)floating point overflow error can be due to memory requirement for the job to run on available RAM machine . In CFX solver manager --> you can slightly increase memory allocation factor from default 1 to 1.2 or 1.4 in solver as shown below . This will increase the memory allocation for this job by 1.2 times .
I hope this will help .