A study of a flexible fiber model and its behavior in DNS of turbulent channel flow
2013 (English)In: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 224, no 10, 2359-2374 p.Article in journal (Refereed) Published
The dynamics of individual flexible fibers in a turbulent flow field have been analyzed, varying their initial position, density and length. A particle-level fiber model has been integrated into a general-purpose, open source computational fluid dynamics code. The fibers are modeled as chains of cylindrical segments connected by ball and socket joints. The equations of motion of the fibers contain the inertia of the segments, the contributions from hydrodynamic forces and torques, and the connectivity forces at the joints. Direct numerical simulation of the incompressible Navier-Stokes equations is used to describe the fluid flow in a plane channel, and a one-way coupling is considered between the fibers and the fluid phase. We investigate the translational motion of fibers by considering the mean square displacement of their trajectories. We find that the fiber motion is primarily governed by velocity correlations of the flow fluctuations. In addition, we show that there is a clear tendency of the thread-like fibers to evolve into complex geometrical configurations in a turbulent flow field, in fashion similar to random conformations of polymer strands subjected to thermal fluctuations in a suspension. Finally, we show that fiber inertia has a significant impact on reorientation timescales of fibers suspended in a turbulent flow field.
Place, publisher, year, edition, pages
Springer, 2013. Vol. 224, no 10, 2359-2374 p.
Paper, Pulp and Fiber Technology Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:liu:diva-98106DOI: 10.1007/s00707-013-0918-yISI: 000325008900010OAI: oai:DiVA.org:liu-98106DiVA: diva2:652141