When this AFT Arrow Steady Solution Method is used elevation data is ignored by the Solver. The output will still show the elevation as entered by the user. Since elevation effects are usually not very important in gas systems, neglecting elevation changes is frequently an acceptable approximation.

An analytical solution to Equations 1, 2 and 5 for adiabatic flow neglecting elevation changes is given by the following (e.g., see Saad, 1993, page 209):

(42)

This equation is valid for real gases as long as the following approximation is accepted:

using a suitably averaged value of c_p. Integrating from 0 to L obtains:

(43)

Equation 43 is then solved for each pipe, using an average value of friction factor and g for each pipe. The solution of Equation 43 typically is iterative where the unknown is M2.