A study of a flexible fiber model and its behavior in DNS of turbulent channel flow
Artikel i vetenskaplig tidskrift, 2013

The dynamics of individual flexible fibers in a turbulent flow field have been analyzed, varying their initial position, density and length. A particlelevel fiber model has been integrated into a general-purpose, open source Computational Fluid Dynamics (CFD) 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 (DNS) 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 time-scales of fibers suspended in a turbulent flow field.

flexible fiber model

CFD

Direct Numerical Simulation (DNS)

Författare

Jelena Andric

Chalmers, Tillämpad mekanik, Strömningslära

Sam Fredriksson

Göteborgs universitet

Stefan B. Lindström

Tekniska Hogskolan vid Linkopings Universitet

Srdjan Sasic

Chalmers, Tillämpad mekanik, Strömningslära

Håkan Nilsson

Chalmers, Tillämpad mekanik, Strömningslära

Acta Mechanica

0001-5970 (ISSN) 1619-6937 (eISSN)

Vol. 224 2359-2374

Ämneskategorier

Strömningsmekanik och akustik

DOI

10.1007/s00707-013-0918-y