Investigation of Turbulent Flow Behavior in Complex Geometries Using Computational Fluid Dynamics

Abstract

This paper examines the behavior of a complex geometry (a 90-degree pipe bend) by undertaking a detailed analysis of the turbulent flow via computational fluid dynamics. k-ω Shear Stress Transport Navier-Stokes simulations with Reynolds number between 10,000 and 50,000 were done with Reynolds-Averaged Navier-Stokes simulations. Systematic mesh refinement was strictly used to achieve grid independence with a value of less than 3% as the Grid Convergence Index. The k-ω SST model showed better predictive power than conventional k-ε models with a mean absolute percentage error of 3.2% in prediction of pressure drop with correlation coefficient R² = 0.998 against experimental results. Findings indicate notable amplification of turbulent kinetic energy (180% gain) in the bend region that is consistent with Re 0.5 scaling law and flow recovery is 5-7 pipe diameters long. Asymmetric velocity distributions and high wall shear stress on inner bend surfaces were observed and the formation of dean vortices and patterns of secondary flows was achieved successfully. The intensity contours of turbulence were found to be highly spatially heterogeneous with maximum values of 18% close to walls. The study sets up the best computational practice in predicting turbulent flow through complex geometries, which gives quantitative advice to the design of industrial piping systems in form of equipment location requirements, the consideration of vibration related to the flow, and erosion-corrosion control policies.