1D-3D coupling algorithm for unsteady gas flow analysis in pipe systems

Abstract

Numerical analysis of intake and exhaust systems in diesel engines has been used to reduce harmful emissions from them. An unsteady gas flow analysis in 3D format of the intake and exhaust systems was inefficient due to the need for a high-resolution workstation and enormous time for analysis. Therefore, a 1D-3D coupling algorithm was developed to resolve this issue. The algorithm was based on the method of characteristics coded in the C language for ID, and utilized ANSYS FLUENT R15.0, a commercial computation fluid dynamics program for 3D. The 1D-3D coupling method employed a User-Defined Function to share the computation between ID and 3D. Numerical analyses of unsteady gas flow in a pipe system were performed under four conditions including ID, 3D, 1D-3D and 3D-1D coupling. As a result, the characteristics of gas flow including pressure and velocity distributions were similar and the calculation time of 1D-3D coupling model was 11.46 times faster than in 3D. Therefore, the proposed algorithm was strongly expected to enhance the results and shorten the calculation time.