Control of a sedimenting elliptical particle by electromagnetic forces

TL;DR

This study demonstrates how electromagnetic forces can effectively control the sedimentation and rotational motion of elliptical particles in fluid, using a specialized numerical method to analyze various control parameters.

Contribution

The paper introduces a novel application of the immersed interface-lattice Boltzmann method for electromagnetic control of sedimenting particles, including systematic analysis of control effects under different conditions.

Findings

Electromagnetic forces can suppress vortex shedding and control particle rotation.

Sedimentation speed can increase by nearly 40% with electromagnetic control.

Control effectiveness is robust across different initial orientations and density ratios.

Abstract

In this paper, the effectiveness of electromagnetic forces on controlling the motion of a sedimenting elliptical particle is investigated using the immersed interface-lattice Boltzmann method (II-LBM), in which a signed distance function is adopted to apply the jump conditions for the II-LBM and to add external electromagnetic forces. First, mechanisms of electromagnetic control on suppressing vorticity generation based on the vorticity equation and vortex shedding based on the streamwise momentum equation are discussed. Then, systematical investigations are performed to quantify and qualify the effects of the electromagnetic control by changing the electromagnetic strength, the initial orientation angle of the elliptical particle, and the density ratio of the particle to the fluid. To demonstrate the control effect of different cases, comparisons of vorticity fields, particle trajectories, orientation angles, and energy transfers of the particles are presented. Results show that the rotational motion of the particle can be well controlled by appropriate magnitudes of electromagnetic forces. In a relatively high solid to fluid density ratio case where vortex shedding appears, the sedimentation speed can increase nearly 40\% and the motion of the particle turns into a steady descent motion once an appropriate magnitude of the electromagnetic force is applied. When the magnitude of the electromagnetic force is excessive, the particle will deviate from the center of the side walls. In addition, the controlling approach is shown to be robust for various initial orientation angles and solid to fluid density ratios.