Simulating flexible fiber suspensions using a scalable immersed boundary algorithm

TL;DR

This paper introduces a scalable immersed boundary algorithm for simulating flexible fiber suspensions in 3D shear flow, accurately capturing fiber dynamics and enabling large-scale simulations for complex suspension behaviors.

Contribution

The authors develop a novel scalable IB algorithm for flexible fibers modeled as Kirchhoff rods, validated against experiments, and demonstrate large-scale suspension simulations.

Findings

Accurately reproduces experimental fiber orbit classes in low Reynolds flows.

Enables simulation of hundreds of fibers on distributed-memory clusters.

Provides a foundation for studying complex suspension phenomena like flocculation.

Abstract

We present an approach for numerically simulating the dynamics of flexible fibers in a three-dimensional shear flow using a scalable immersed boundary (IB) algorithm based on Guermond and Minev's pseudo-compressible fluid solver. The fibers are treated as one-dimensional Kirchhoff rods that resist stretching, bending, and twisting, within the generalized IB framework. We perform a careful numerical comparison against experiments on single fibers performed by S. G. Mason and co-workers, who categorized the fiber dynamics into several distinct orbit classes. We show that the orbit class may be determined using a single dimensionless parameter for low Reynolds flows. Lastly, we simulate dilute suspensions containing up to hundreds of fibers using a distributed- memory computer cluster. These simulations serve as a stepping stone for studying more complex suspension dynamics including non-dilute suspensions and aggregation of fibers (also known as flocculation).