Development of a 3-D laminar Navier-Stokes solver for separated channel flows

Abstract

This study involves the development of a 3-D laminar Navier-Stokes solver with finite volume method in C++ language and investigation of 3-D separated channel flows. The missing parts of 3-D numerical implementation in Computational Fluid Dynamic books and articles are tried to be revealed within this study. To achieve these, the details of the discretization methods, implementation of boundary conditions and solution algorithm are explained. Besides, a more generalized form of the coefficients of the discretized momentum and pressure correction equations including boundary nodes are proposed. The use of artificial viscosity method achieves converting the conventional channel geometry into different channel geometries. Validation of the code is made investigating developing channel flow, artificial viscosity method and backward facing step flow. There exists an excellent agreement between present study and analytical results and experimental data. The simulation of a 3-D backward facing step is given in detail and the flow structure behind the step geometry is investigated. It was showed that complex three-dimensional flow develops behind the step with reverse and swirling flow regions. The "jet-like" flow and the impingement to the bottom wall are found to be responsible from the minimum on the reattachment line where thestreamwise component of the wall shear stress is zero. The effect of channel expansion ratio on flow structure and pressure recovery is investigated and it is found that as expansion ratio increases, the reattachment line moves toward downstream of channel and the expansion loss coefficient increases.