Comparison of finite-volume method and method of characteristics for simulating transient flow in natural-gas pipeline

Abstract

In this study, two numerical methods of modeling transient flow in a single natural-gas pipeline are analyzed and compared. Specifically, the pressure-based finite-volume method (FVM)—which uses a collocated mesh with the total variation diminishing (TVD) scheme—and the conventional implicit method of characteristics (iMOC)—which uses an inertial multiplier—are considered. Network analysis is an essential part of the design and operation of natural-gas pipelines. Studies have been conducted on various numerical methods to analyze the transient flow of natural-gas pipelines, but comparative studies on the characteristics and relative advantages and disadvantages of the methods are inadequate; therefore, it is necessary to analyze and compare the underlying numerical methods to ensure their reliability. Accordingly, two test cases are considered: slow transient flow validated with experimental data, and fast transient flow with an artificial problem including valve stroking. The two methods are examined quantitatively and qualitatively. The order of accuracy, determined using the grid-convergence index, and the computational cost are evaluated for quantitative analysis. Overall, the pressure-based FVM with the TVD scheme outperforms iMOC for both slow and fast transient problems.