Motion of asymmetric bodies in two-dimensional shear flow

Roggeveen, James V.; Stone, Howard A.

doi:10.1017/jfm.2022.203

Cited by 5 publications

(4 citation statements)

References 61 publications

(175 reference statements)

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“…). This identification of an active spheroidal particle behaving like a sphere in 3-D shear flow complements recent work in which a passive non-spheroidal particle (a symmetric boomerang with angle ) was shown to behave like a sphere in two-dimensional (2-D) shear flow (Roggeveen & Stone 2022).…”

Section: Results and Conclusionsupporting

confidence: 84%

Generalised Jeffery's equations for rapidly spinning particles. Part 1. Spheroids

Dalwadi,

Moreau,

Gaffney

et al. 2024

J. Fluid Mech.

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The observed behaviour of passive objects in simple flows can be surprisingly intricate, and is complicated further by object activity. Inspired by the motility of bacterial swimmers, in this two-part study we examine the three-dimensional motion of rigid active particles in shear Stokes flow, focusing on bodies that induce rapid rotation as part of their activity. In Part 1 we develop a multiscale framework to investigate these emergent dynamics and apply it to simple spheroidal objects. In Part 2 (Dalwadi et al., J. Fluid Mech., vol. 979, 2024, A2) we apply our framework to understand the emergent dynamics of more complex shapes; helicoidal objects with chirality. Via a multiple scales asymptotic analysis for nonlinear systems, we systematically derive emergent equations of motion for long-term trajectories that explicitly account for the strong (leading-order) effects of fast spinning. Supported by numerical examples, we constructively link these effective dynamics to the well-known Jeffery's orbits for passive spheroids, deriving an explicit closed-form expression for the effective shape of the active particle, broadening the scope of Jeffery's seminal study to spinning spheroids.

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Section: Results and Conclusionsupporting

confidence: 84%

Generalised Jeffery's equations for rapidly spinning particles. Part 1. Spheroids

Dalwadi,

Moreau,

Gaffney

et al. 2024

J. Fluid Mech.

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“…We adapt the hydrodynamic calculations outlined by Roggeveen and Stone [91] and Ganguly and Gupta [42] to study the motion of a bent rod actuator, Figure 1. We employ the non-dimensional particle geometry as described by Ganguly and Gupta [42].…”

Section: Problem Setupmentioning

confidence: 99%

“…The mobility coefficients M are determined by numerically inverting the resistance coefficients (multiplied by a minus sign) determined by Roggeveen and Stone (Eq. 3.5 in their work) [91] using the Python module Scipy with the linalg.inv function. Using the results from Ganguly and Gupta [42], calculated with the reciprocal theorem, we express the effective force and torque in terms of a velocity on the surface of the bent rod actuator,…”

Section: Slender-body Theorymentioning

confidence: 99%

“…First, in Section 2, we expand the theoretical framework developed by Roggeveen and Stone [91] and Ganguly and Gupta [42] to compute the motion of the actuator due to both self-diffusiophoresis as well as hinge articulations. In Section 3.1 and Section 3.2, we calculate the trajectories of the actuator moving due to reciprocal hinge articulations (Figure 4) and non-reciprocal hinge articulations (Figure 5).…”

Section: Introductionmentioning

confidence: 99%

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Motion of an active bent rod with an articulating hinge: exploring mechanical and chemical modes of swimming

Raj,

Ganguly,

Becker

et al. 2023

Front. Phys.

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Swimming at the microscale typically involves two modes of motion: mechanical propulsion and propulsion due to field interactions. During mechanical propulsion, particles swim by reconfiguring their geometry. When propelled by field interactions, body forces such as phoretic interactions drive mobility. In this work, we employ slender-body theory to explore how a bent rod actuator propels due to a mechanical mode of swimming via hinge articulations and due to a chemical mode of swimming via diffusiophoretic interactions with a solute field. Although previous theoretical studies have examined mechanical and chemical modes of swimming in isolation, the simultaneous investigation of both modes has remained unexplored. For the mechanical mode of swimming, our calculations, both numerical and analytical, recover Purcell’s scallop theorem and show that the bent rod actuator experiences zero net displacement during reciprocal motion. Additionally, we calculate the trajectories traced by a bent rod actuator under a non-reciprocal hinge articulation, revealing that these trajectories are influenced by the amplitude of the hinge articulation, geometric asymmetry, and the angular velocity distribution between the two arms of the bent rod actuator. We provide intuitive explanations for these effects using free-body diagrams. Furthermore, we explore the motion induced by simultaneous hinge articulations and self-diffusiophoresis. We observe that hinge articulations can modify the effective phoretic forces and torques acting on the bent rod actuator, either supporting or impeding propulsion. Additionally, during self-diffusiophoretic propulsion, reciprocal hinge articulations no longer result in zero net displacement. In summary, our findings chart a new direction for designing micron-sized objects that harness both mechanical and chemical modes of propulsion synchronously, offering a mechanism to enact control over trajectories.

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Metaball-Imaging discrete element lattice Boltzmann method for fluid–particle system of complex morphologies with case studies

et al. 2023

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Fluid-particle systems are highly sensitive to particle morphologies. While many attempts have been made on shape descriptors and coupling schemes, how to simulate the particle-particle and particle-fluid interactions with a balance between accuracy and efficiency is still a challenge, especially when complex-shaped particles are considered. This study presents a Metaball-Imaging (MI) based Discrete Element Lattice Boltzmann Method (DELBM) for fluid simulations with irregular shaped particles. The major innovation is the MI algorithm to capture the real grain shape for DELBM simulations, where the Metaball function is utilized as the mathematical representation due to its versatile and efficient expressiveness of complex shapes. The contact detection is tackled robustly by gradient calculation of the closest point with a Newton-Raphson based scheme. And the coupling with LBM is accomplished by a classic sharp-interface scheme. As for refiling, a local refiling algorithm based on the bounce back rule is implemented. Validations on three settling experiments of irregular-shaped natural cobblestones indicate the proposed model to be effective and powerful in probing micromechanics of irregular-shaped granular media immersed in fluid systems. The potential of this model on studies of shape-induced physical processes is further investigated with numerical examples on the "drafting, kissing and tumbling" phenomenon of pair particles in various shapes.

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Motion of asymmetric bodies in two-dimensional shear flow

Cited by 5 publications

References 61 publications

Generalised Jeffery's equations for rapidly spinning particles. Part 1. Spheroids

Generalised Jeffery's equations for rapidly spinning particles. Part 1. Spheroids

Motion of an active bent rod with an articulating hinge: exploring mechanical and chemical modes of swimming

Metaball-Imaging discrete element lattice Boltzmann method for fluid–particle system of complex morphologies with case studies

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