Vortex Interactions in Turbulent Flow through 90-degree Bend Pipe: A Parametric Study

Abstract

• To identify the vortex structures using invariants of the complex conjugate eigenvalues of the velocity gradient tensor, in a mean turbulent flow field. • Swirling strength and incipient turbulence characteristics of flow with effect of parameters such as Reynolds number and curvature ratio. The Reynolds number 1000 to 0.1 million and curvature ratio 0.01 to 0.2. • Reynolds averaged Navier-Stoke’s equations solved for a steady state incompressible flow, using the Reynolds stress model to close turbulence-related variables. • There is a shift in location of maximum swirling strength in bend when curvature varied. However, insignificant change is observed in vortex structures with Reynolds number variation. • With increase in curvature swirling strength maxima shifts away from the bend inlet to the vortex arms. • The turbulent kinetic energy is less at the inner bend section, which shows shifting of perturbations to the outer section of the bend. The rate of dissipation is also observed to be significantly reduced. • Intensity of perturbations is found to be greater in a narrower bend.