Analysis of underground ventilation networks utilizing the skyline nodal pressure method

A calculation system for the analysis of underground ventilation networks by means of a nodal pressure method using the skyline modified Choleski's decomposition scheme, named 'skyline nodal pressure method', has been studied. The generalized linear equations for solving steady state ventilation airflow have been developed using a connective function between nodes. The skyline decomposition scheme has an advantage on rapid convergence and the sake of computer memory space as compared with other schemes. Five examples of venti-lation networks have been calculated using a popular personal computer. A convergence criterion, that the maximum error of the summed airflow quantity in continuity at each node is less than 0.1 m3/min, was used for the calculations. Under the conditions that the fan-pressure is given as a constant value and that the acceleration factor is set at 1.4, the number of the iterations until convergence was not more than 13 for each network. The calcu-lation processing time by the skyline nodal method is roughly in proportion to the total number of nodes to the 3/2 power.