A CFD Study of Steady Fully Developed Laminar Flow Through a 90-Degree Bend Pipe with a Square Cross-Sectional Area

Fluid flow through a closed curved conduit has always been a topic of extensive research, as it has many practical and industrial applications. The flow is generally characterized by a presence of secondary flow, vortical motions and pressure losses for different flow regimes. These observed irregularities may positively or negatively impact the flow. They are beneficial for cases where mixing of fluids is required, usually observed for multiphase flow regimes or detrimental for cases involving particles in the fluid. There are also instances where a particle-laden fluid transported through the curved pipe was directly related to corrosion- erosion related problems. A significant amount of revenue is lost every year to control and deal with the problem. In this thesis, with the help of CFD, steady laminar flow through a curved 90-degree pipe with a square cross-sectional area is studied. The initiation phenomena of the secondary flow for non-vortical and vortical types were analyzed. The presence of a transversal pressure gradient playing the pivotal role in determining the secondary flow of the vortical type was found. Further analysis with varying Reynolds number for the flow as well as varying Radius of curvature of the bend geometry was also undertaken. Studies involving different types of boundary conditions and the introduction of particles in the flow were also briefly analyzed in the later stages of the thesis. It was concluded that assigning the slip boundary conditions to the wall nearly reduces the intensity of secondary flow, both non-vortical and vortical type in comparison to the main axial flow and also a decrease of more than 80 % in erosion was observed for low Stokes numbers