How inertial lift affects the dynamics of a microswimmer in Poiseuille flow

Abstract

The transport of motile microorganisms is strongly influenced by fluid flows that are ubiquitous in biological environments. Here we demonstrate the impact of fluid inertia. We analyze the dynamics of a microswimmer in pressure-driven Poiseuille flow, where fluid inertia is small but non-negligible. Using perturbation theory and the reciprocal theorem, we show that in addition to the classical inertial lift of passive particles, the active nature generates a ‘swimming lift’, which we evaluate for neutral and pusher/puller-type swimmers. Accounting for fluid inertia engenders a rich spectrum of complex dynamics including bistable states, where tumbling coexists with stable centerline swimming or swinging. The dynamics is sensitive to the swimmer’s hydrodynamic signature and goes well beyond the findings at vanishing fluid inertia. Our work will have non-trivial implications on the transport and dispersion of active suspensions in microchannels.

Ciliary propulsion through non-uniform flows

“…Notably, they assumed that the swimmer propelled with the velocity v = (2B 1 /3)e of a squirmer in a quiescent flow, where e is the swimmer's orientation. The same assumption appears to have been made by Choudhary et al (2022) in their analysis of the effects of inertia on the motion of a channel-confined squirmer in a Poiseuille flow. In this study, they showed that inertia and the type of squirmer (neutral pusher/puller) play a critical role in determining the stability of the squirmer's dynamics.…”

“…Focusing specifically on Poiseuille flows ubiquitous in the biological microcirculation, experiments dating back to the 1960s have explored its effect on the dynamics of a suspension of particles (Goldsmith & Mason 1961;Segré & Silberberg 1961). Later, Kessler investigated the influence of Poiseuille flows on the directed locomotion of algal cells (Kessler 1985) whereas, much more recently, other investigators have reported Poiseuille flows' effects on the dynamics, orientations and trajectories of biological microorganisms Choudhary et al 2022;Omori et al 2022;Walker et al 2022), artificial microswimmers (Acemoglu & Yesilyurt 2015) and vesicles (Danker, Vlahovska & Misbah 2009;Agarwal & Biros 2020). have investigated the influence of a Poiseuille flow on the swinging and tumbling motion of microswimmers in a channel by reducing the problem to a dynamical system for the position and orientation of the swimmer.…”

Lattice Boltzmann Simulations of Two Linear Microswimmers Using the Immersed Boundary Method

“…2 show that while the Reynolds number of the swimmer is relatively small (Re swimm ∼ 10 −4 ), the Reynolds number associated with the beads at maximum speed is larger by two orders of magnitude (Re bead ∼ 10 −2 ). Indeed, recent works have shown that when the Reynolds number approaches unity, swimming protocols that exploit inertia can become operational [33,60]. However, the relative mismatch between the Oseen predictions and the numerical results suggests that fluid inertia may not be the only cause of such a discrepancy.…”

A novel Human Conception Optimizer for solving optimization problems

“…The Poiseuille profile is used to find the speed of the sperm cells. It tells how fast the sperm cells are moving at each point within the uterus 65 , 66 .…”

“…2 a. At the specific radius ( r ), the velocity is formulated as 65 , 66 : where P is the pressure difference, L is length of a pipe with radius a , is dynamic viscosity.…”