A Warning message in AFT xStream

Full Message text is:

Energy may not be balanced at Junction X (total = Y)

 

This warning alerts users that the converged energy balance results may be incorrect for the AFT Arrow Steady Solution. Once a converged solution is obtained, AFT xStream checks all junctions to ensure an energy balance exists. It compares the imbalance to the mass flow weighted enthalpy tolerance, and when the imbalance exceeds the tolerance, this warning is generated.

If the magnitude of the energy imbalance is close to the tolerance specified, it is generally safe to ignore this warning, although it may make sense to reduce tolerances further and rerun the model.

If the magnitude of the energy imbalance is large, the converged solution that may be incorrect. When a large imbalance exists, it may be an indicator the model is not realistic.

These warnings should always be reviewed in detail, and the user should perform hand calculations on the energy balance at the affected junctions to verify whether an acceptable solution exists.

Note: This warning will usually occur when you assign isothermal boundary conditions to pipes in your model. If pipes are forced to flow at the isothermal temperature specified, it is usually not possible to balance energy at the junctions. The warning can be ignored in such circumstances, because the energy imbalance is a natural result of the isothermal assumption.