Session: 08-07-01 Internal Flows & Fluid–Structure Interaction in Riser and Pipeline Systems

Submission Number: 180242

Influences of the Wall Roughness on the Dean Vortices Behind a Pipe Bend 

Fluid flow through bend pipes, which is commonly observed in subsea piping systems, generates secondary, counter-rotating vortices known as Dean flow. While the dynamics and spatial evolutions of the Dean vortices behind the bend part of the pipeline have been studied extensively, they are inside pipe with smooth walls. However, the roughness of the pipeline wall is inherent in additive manufacturing and can also develop over time through the deposition or corrosion. The influences of the surface roughness behind the bend part on the decay of these vortices remain largely unaddressed.

In the present study, the influences of the wall roughness on the decay of the Dean vortices are investigated using the Computational Fluid Dynamics (CFD) simulations for an incompressible, single-phase flow at low Reynolds numbers. A 90-degree bend is considered and a systematic sinusoidal roughness is used to model the roughness behind the bend part. The study systematically explores the effects of the varying roughness height, the wavelength of the roughness element and the radius of the bend curvature on the flow past the bend part. The decay of Dean vortices is quantified by analyzing axial vorticity, Q-criterion, perturbation velocity, and the flow induced wall shear stress.

The results indicate that increasing roughness height accelerates the development of the axial velocity profile but will also generate high-magnitude vorticities within the roughness elements at the wall. It is also found that increasing roughness height will slightly reduce the azimuthal-averaged wall shear stress in the axial direction. Similarly, reducing the wavelength of the roughness element also reduces wall shear stress. Shorter wavelengths will cause the Dean vortices to propagate further along the pipe, which slows their decay process.

Presenting Author: Guang Yin University of Stavanger

Presenting Author Biography: 2018-2021 Postdoc, University of Stavanger
2021-2025 Researcher, University of Stavanger
2025- Associate Professor, University of Stavanger

Authors:

Liz Tipton Cornell University
Guang Yin University of Stavanger
Muk Ong University of Stavanger