Numerical Investigation Using Compressible Navier-Stokes Equations for Low-Speed Flow in Pipes with Varying Cross Sections

Abstract

An explicit method of lines for solving compressible Navier-Stokes equations which consists of the rational Runge-Kutta time stepping scheme and central finite differencing, is applied to compute low-speed flows in pipes with varying cross sections. Low-Reynolds-number flow in a suddenly expanding pipe is calculated as a test problem, in order to assess the forms of the basic equations in general coordinates and to confirm the accuracy of the method. The results show that the quasi-conservation law form is more reliable than the full conservation law form, and the calculated reattachment distance is in good agreement with other established results. In the following, calculations of the flows in a pipe with a valve are carried out. The results are compared with experimental results. The discharge coefficients and flow patterns for each valve lift are accurately obtained.