A novel implicit method of characteristics using pressure-referenced correction for transient flow in natural gas pipelines

This paper presents a novel implicit method of characteristics (MOC) utilizing pressure-referenced characteristic line correction that ensures the efficiency and reliability of transient flow analyses for natural gas pipelines. The conventional implicit MOC utilizes an inertial multiplier that results in issues associated with numerical dispersion and convergence in fast transient flows. This increases the computational cost compared to that of the explicit MOC, preventing the practical application of the implicit MOC. To address this issue, a pressure referenced characteristic line correction method that guarantees second-order accuracy is proposed. The proposed method coordinates the characteristic line and corrects it using pressure gradients to enhance the computational efficiency and fidelity of the system. Quantitative and qualitative analyses were performed to verify the performance of the proposed method. It was confirmed that the proposed method outperformed the conventional technique in terms of computational cost and reliability when applied to fast transient flows. Compared with those of the conventional method, there were 40-fold and one-half reductions in computational cost and root mean square error, respectively, under a Courant-Friedrich-Lewy condition of 10.0. Additionally, the feasibility of the proposed method in practical pipeline analysis applications was confirmed through verification experiments for a real-world slow transient problem.

Automated summary

This paper presents a novel implicit method of characteristics (MOC) utilizing pressure-referenced characteristic line correction that ensures the efficiency and reliability of transient flow analyses for natural gas pipelines. The proposed method coordinates the characteristic line and corrects it using pressure gradients to enhance the computational efficiency and fidelity of the system.