Nodes defining system geometry are assigned with inter-connecting elements. The elements include components such as pipes, tees, reducers, valves, and orifice plates. Element transfer matrices are integrated into an overall system matrix composed of linear equations with complex coefficients and variables. The variables include RMS values of pulsating pressure and volume flow velocity at each node. A sparse variant of Gaussian elimination for the solution of unsymmetrical equations solves for the results.
The transfer matrices are based on a comprehensive body of semi-empirical equations and data acquired through a rigorous, experimental testing program conducted at the Nova facilities and the University of Calgary. Gas properties are calculated using Benedict-Webb-Rubin-Starling (BWRS), Soave-Redlich-Kwong (SRK), or Peng-Robinson (PR) equations of state. PULS also accepts user-defined fluid properties.