Decay of secondary motion downstream bends in turbulent pipe flows

• DOI: 10.1063/5.0129339
• Publication Date: 2022-12-09T16:35:15Z
• Authors: Kasper Gram Bilde; Kim Sørensen; Jakob Hærvig
• Keywords: Secondary flow; Pipe flow; Intensity

Decay of secondary motion downstream 180° pipe bends is investigated using large-eddy simulations for the bend radii 1≤rB/dh≤3.375 at a Reynolds number Reh=10 000. The velocity and turbulence characteristics are validated against experimental data straight section as well direct numerical 90° bend. As radius decreases, larger magnitude intensity induced immediately bend, largest magnitude, highest gradient decay observed. result, recovery length needed to reestablish profile decreases. Turbulence transported higher rate, indicating that driven by transport. Secondary motions curvature increases. results show how in flow moves At outlet dominating walls within bulk flow. fluid further downstream, flows dominate close walls, x/dh=5, negligible difference observed different radii.