KNOWN ISSUE: Incorrect results for Cv if using the IAPWS steam table library (Class 3 Error)


SYMPTOM:
Using Cv (specific heat at constant volume) in an expression or user FORTRAN could give incorrect answers when using the IAPWS (steam table) library.

PROBLEM:
The CFX-Solver incorrectly calculates specific heat at constant volume when running the IAPWS (steam table) library for pressure and temperatures in region 2. Region 2 is the gas phase (dry steam) region, below the vapour pressure curve on a P vs T diagram. It spans the entire valid temperature range from 273.15 [K] to 1073.15 [K] and pressure range from the triple point to 100 [MPa].

Solutions computed by the CFX-Solver are in general not affected by the Cv calculations. However, any expressions or user FORTRAN which use Cv will be incorrect if the p or T values fall in region 2.

WORKAROUND:
No workaround is currently available.

FIXED IN:
ANSYS CFX Release 12.1. A custom executable for ANSYS CFX 12.0 is available on request.





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