Modeling the dynamics of flow in gas pipelines

The description of nonstationary one-dimensional flow of a nonideal gas in a pipe is treated with the goal of developing a mathematical description of flow and pressure (density) dynamics adequate for creating a simulation model of large pipeline networks. The work is started from Newton's equation of motion, the continuity equation, and the energy equation. Because hundreds of these sets of equations are to be repeatedly and simultaneously solved when a large network is simulated, a simple, yet accurate mathematical description is desirable. To this end, a detailed analysis was performed to determine the relationships among 1) space discretization 2) terms of Newton's equation, and 3) frequency of the dynamic processes occuring in the system. Respecting the influence of all these factors, the dynamic description of a pipe is discussed for two different modes of space discretization and the quantitative rules for space discretization are given.