AFT xStream offers multiple fluid databases for users to choose from in the Fluids panel of the Analysis Setup window. Each database has benefits and drawbacks.

If the model is defined using the ASME Steam, Chempak, or NIST REFPROP databases and is experiencing convergence problems, the user should simplify the model by choosing a fluid from the AFT Standard fluid database. The fluid models used for this database are simplified from those in the other databases, and often allow AFT xStream to find a solution more easily.

Once the user has a model that runs well using an AFT Standard fluid, they can return to the more complex fluid databases.

It should also be noted that users are strongly encouraged to only use AFT Standard fluids in their AFT xStream model. The increased accuracy of other models is almost always outweighed by the increased run time associated with the more complex fluids.