Computations of the Three-Dimensional Flow Field in a Tube with Sudden Contraction

Numerical computations of the three-dimensional laminar flow field in a tube with a sudden contraction of cross sectional area, having an inclined angle of 30 deg, were carried out. In this study, the full incompressible Navier-Stokes equations in generalized curvilinear coordinates, using a pseudocompressibility approach for continuity equation, were solved by the implicit, approximately factored scheme of Beam and Warming. Multi-block computational grids of complete continuity at block interfaces were employed. The predicted results for streamwise velocity profiles on validation case with no inclined angle were in very good agreement with the measured data. Computational results showed the nature of complex flow fields within the inclined small tube, including strong pressure-driven secondary flows in the cross stream induced by the effect of streamline curvature. Furthermore, it was found in this study that asymmetric secondary flows were induced in the Reynolds number range above assumed laminar How regime considered. Computed results were also discussed for the topology of such flows.