Pipe X Computing Section Length Change Calculation Failed to Converge

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Pipe X Computing Section Length Change calculation failed to continue towards convergence. Error value = Y, Tolerance = Z (Code #305)

Explanation

The Solver failed to meet internal tolerances while marching down the pipe segments and performing compressible flow calculations. Some results may not be accurate. This can happen if a Mach Number March or one of the hybrid methods is used as the Solution Method. The Solver is trying to break the pipe into segments that are reported in the Axial Points tab of the Output but the Mach Number may be changing very rapidly, especially towards the end of the pipe if there is sonic choking.

Required Action

Check to see if the Sonic Choking tab is present in the Output. If the pipe listed in the warning is upstream of a choke point, then it may be helpful to enter a CdA for Sonic Choking in the downstream junction properties.

If the pipe is experiencing endpoint choking, then it may be helpful to adjust the Mach Number Increment on the Solution Method panel. The default Mach Number Increment is 0.01, and you can try changing to 0.1. Making the increment too large may result in too few axial points to effectively capture the changing fluid properties.

If the error value and tolerance are close, then the Warning may be less severe and can potentially be ignored depending on your engineering judgment and review of the results.