On the DLM/FD methods for simulating neutrally buoyant swimmer motion in non-Newtonian shear thinning fluids

TL;DR

This paper extends the DLM/FD method to simulate neutrally buoyant particles of non-symmetric shape in non-Newtonian shear thinning fluids, demonstrating its effectiveness through numerical comparisons and analyzing swimmer dynamics.

Contribution

It generalizes the DLM/FD method for complex particle shapes in non-Newtonian fluids and applies it to analyze swimmer motion and flow characteristics.

Findings

Shear thinning increases swimmer speed.

Shear thinning reduces the critical Reynolds number.

Numerical solutions match exact flow solutions.

Abstract

In this article we discuss the generalization of a Lagrange multiplier based fictitious domain (DLM/FD) method to simulating the motion of neutrally buoyant particles of non-symmetric shape in non-Newtonian shear thinning fluids. Numerical solutions of steady Poiseuille flow of non-Newtonian shear thinning fluids are compared with the exact solutions in a two-dimensional channel. Concerning a self-propelled swimmer formed by two disks, the effect of shear thinning makes the swimmer moving faster and decreases the critical Reynolds number (for the moving direction changing to the opposite one) when decreasing the value of the power index in the Carreau-Bird model.