AFT Arrow uses a modified Newton-Raphson matrix method to obtain a system level balance of mass, energy and concentration. When the Solver is finished, the continuity, energy, and concentration equations are satisfied at all branching sections. Once solved, AFT Arrow goes back and sums up all mass flows, energy and concentrations at each branch to verify that these equations are satisfied.

After the Solver converges, AFT Arrow loops over each junction and adds up the inflow and outflow of mass, energy and concentrations and compares the sum to the solution tolerances. If it appears that any junction is out of tolerance, a warning is given in the output.

In the Solution Balance Summary table AFT Arrow provides additional information on the balance at each junction. This table can be displayed by selecting the option in the Output Control window General Output folder. Figure 1 shows an example of the Solution Balance Summary table.