Swimming Microorganisms Research Articles

Cattaneo–Christov double diffusive non-Newtonian nanofluid flow over a rotating disk of variable thickness influenced by swimming microorganisms and velocity slip condition

This exploration examines the effects of the Cattaneo–Christov double diffusion in the Ostwald-de-Waele nanofluid flow on a rotating disk with varying thicknesses. The incorporation of the impacts of the bioconvection microorganisms increases the stability of the nanofluids. The slip boundary constraint is taken at the disk. The flow system is based on the Buongiorno nanofluid model. The envisioned fluid flow model incorporates heat transmission properties that are affected by nanoparticle volume fraction, Brownian motion, and thermophoresis. The numerical software bvp4c method is affianced. The presented diagrams portray the correlation of the protuberant parameters with the associated profiles given with cogent arguments. It is heeded that higher estimates of the thermal and solutal relaxation parameters dwindled the thermal and mass profiles. Furthermore, the motile microorganism distribution is diminished for larger counts of the Peclet number. A comparison table is also included to justify the truthfulness of the proposed model.

Sisko nanofluid flow through exponential stretching sheet with swimming of motile gyrotactic microorganisms: An application to nanoengineering

Abstract The swimming of motile gyrotactic microorganism’s phenomenon has recently become one of the most important topics in research due to its applicability in biotechnology, many biological systems, and numerous engineering fields. The gyrotactic microorganisms improve the stability of the nanofluids and enhance the mass/heat transmission. This research investigates the MHD fluid flow of a dissipative Sisko nanofluid containing microorganisms moving along an exponentially stretched sheet in the current framework. The mathematical model comprises equations that encompass the preservation of mass, momentum, energy, nanoparticle concentration, and microorganisms. The equations that govern are more complicated because of nonlinearity, and therefore to obtain the combination of ordinary differential equations, similarity transformations are utilized. The numerical results for the converted mathematical model are carried out with the help of the bvp4c solver. The resulting findings are compared to other studies that have already been published, and a high level of precision is found. The graphical explanations for velocity, temperature, and nanoparticles volume fraction distribution are shown with physical importance. Physical characteristics like Peclet number, Sisko fluid parameter, thermophoresis and Brownian motion parameter, and Hartmann number are taken into consideration for their effects. Based on the numerical outcomes, the bioconvection Peclet number enhances the density of mobile microorganisms, whereas thermal radiation contributes to an elevation in temperature. The velocity field decreases with the enhancement of magnetic parameter; however, the temperature field increases with increased magnetic parameter and thermophoresis parameter augmentation. Our numerical findings are ground breaking and distinctive, and they are used in microfluidic devices including micro instruments, sleeve electrodes, and nerve development electrodes. This study has various applications in nanoengineering, including nanomaterial synthesis, drug delivery systems, bioengineering, nanoscale heat transfer, environmental engineering.

Generalized slip impact of Casson nanofluid through cylinder implanted in swimming gyrotactic microorganisms

In this paper, the self-propelled movement on gyrotactic swimming microorganisms into this generalized slip flow by nanoliquid over the stretching cylinder with strong magnetic field is discussed. Constant wall temperature was pretended as well as the Nield conditions of boundary. The intuitive non-Newtonian particulate suspension was included into applying Casson fluid by the base liquid and nanoparticles. This formation on the bio-mathematical model gives the boundary value problem by the nonlinear partial differential equations. Primly, modeled numerical system was converted to nondimensional against this help on acceptable scaling variables and the bvp4c technique was used to acquire the mathematical outcomes on the governing system. This graphical description by significant parameters and their physical performance was widely studied. The Prandtl number has the maximum contribution (112.595%) along the selected physical parameters, whereas the Brownian motion has the least (0.00165%) heat transfer rate. Anyhow, Casson fluid was established for much helpful suspension of this method on fabrication and coatings, etc. Therefore, this magnetic field performs like the resistive force of that fluid motion, and higher energy was enlarged into the structure exhibiting strong thermal radiation.

Numerical simulation of bioconvectional nanofluidic flow in the presence of activation energy past a stretching cylinder subject to swimming micro-organisms

Numerical simulation of bioconvectional nanofluidic flow in the presence of activation energy past a stretching cylinder subject to swimming micro-organisms

Interplay between Brownian and hydrodynamic tracer diffusion in suspensions of swimming microorganisms

The general problem of tracer diffusion in non-equilibrium baths is important in a wide range of systems, from the cellular level to geographical length scales. In this paper, we revisit the archetypical example of such a system: a collection of small passive particles immersed in a dilute suspension of non-interacting dipolar microswimmers, representing bacteria or algae. In particular, we consider the interplay between thermal (Brownian) diffusion and hydrodynamic (active) diffusion due to the persistent advection of tracers by microswimmer flow fields. Previously, it has been argued that even a moderate amount of Brownian diffusion is sufficient to significantly reduce the persistence time of tracer advection, leading to a significantly reduced value of the effective active diffusion coefficient $D_A$ compared to the non-Brownian case. Here, we show by large-scale simulations and kinetic theory that this effect is in fact practically relevant only for microswimmers that effectively remain stationary while still stirring up the surrounding fluid – so-called shakers. In contrast, for moderate and high values of the swimming speed, relevant for biological microswimmer suspensions, the effect of Brownian motion on $D_A$ is negligible, leading to the effects of advection by microswimmers and Brownian motion being additive. This conclusion contrasts with previous results from the literature, and encourages a reinterpretation of recent experimental measurements of $D_A$ for tracer particles of varying size in bacterial suspensions.

Correction to: Swimming of Gyrotactic Microorganisms in Unsteady Flow of Eyring Powell Nanofluid with Variable Thermal Features: Some Bio-technology Applications

Correction to: Swimming of Gyrotactic Microorganisms in Unsteady Flow of Eyring Powell Nanofluid with Variable Thermal Features: Some Bio-technology Applications

Flow-induced diffusion in a packed lattice of squirmers

Mass transport in suspensions of swimming microorganisms is one of the most important factors for the colonisation and growth of microorganisms. Hydrodynamic interactions among swimming microorganisms play an important role in mass transport, especially in highly concentrated suspensions. To elucidate the influence of highly concentrated cells on mass transport, we numerically simulated mass transport in lattices of squirmers that were fixed in space and oriented in the same direction. The effects of different volume fractions, Péclet numbers ( $Pe$ ) and lattice configurations on mass transport were quantified by tracking Lagrangian material points that move with background flow with Brownian diffusivity. Although the flow field became periodic in space and each streamline basically extended in one direction, the motion of tracer particles became diffusive over long durations due to Brownian motion and cross-flows. Flow-induced diffusion was anisotropic and significantly enhanced over Brownian diffusion in the longitudinal direction. We also investigated mass transport in random configurations of squirmers to reproduce more general conditions. Similar enhanced diffusion was also observed in the random configurations, indicating that the flow-induced diffusion appears regardless of the configurations. The present flow-induced diffusion did not follow $Pe$ dependency of the conventional Taylor dispersion due to the cross-flows. The time and velocity scales were proposed, which enabled us to predict the flow-induced diffusivity from the data of the flow field and Brownian diffusivity without solving the mass conservation equation. The findings reported here improve our understanding of the transport phenomena in packed suspensions of swimming microorganisms.

Magnetohydrodynamic micropolar nanofluid flow over a vertically elongating sheet containing gyrotactic microorganisms with temperature-dependent viscosity

Magnetohydrodynamic bioconvective micropolar nanofluid flow with migrating microorganisms opens up an intriguing new field in materials science. The distribution of particles during processing, such as metal casting, polymer extrusion, etc., can affect material characteristics and final product quality. So, the current research examines magnetohydrodynamic micropolar nanofluid flow over a vertically extending material in the presence of swimming microorganisms. The mathematical model also considers the temperature dependence of dynamic viscosity with thermal radiation using the Rosseland approximation, Brownian diffusion, and the thermo-migration of microscopic particles. Similarity variables are used to convert the partial derivatives to ordinary derivatives. Then the Runge-Kutta-Gill method is used with the shooting technique to obtain a numerical solution to the resulting set of equations. Various tables and graphs are included to illustrate the impact of the emerging parameters on the flow fields. Results show that an increase in the material parameter improves fluid mobility but decreases the skin friction coefficient, whereas the magnetic field term exhibits the opposite behaviour due to friction induced by the Lorentz force. The analysis shows that the thermal field significantly expands as the thermo-migration of tiny particles and Brownian motion get stronger.

The effect of axisymmetric confinement on propulsion of a three-sphere microswimmer

Swimming at the microscale has recently garnered substantial attention due to the fundamental biological significance of swimming microorganisms and the wide range of biomedical applications for artificial microswimmers. These microswimmers invariably find themselves surrounded by different confining boundaries, which can impact their locomotion in significant and diverse ways. In this work, we employ a widely used three-sphere swimmer model to investigate the effect of confinement on swimming at low Reynolds numbers. We conduct theoretical analysis via the point-particle approximation and numerical simulations based on the finite element method to examine the motion of the swimmer along the centerline in a capillary tube. The axisymmetric configuration reduces the motion to one-dimensional movement, which allows us to quantify how the degree of confinement affects the propulsion speed in a simple manner. Our results show that the confinement does not significantly affect the propulsion speed until the ratio of the radius of the tube to the radius of the sphere is in the range of O(1)−O(10), where the swimmer undergoes substantial reduction in its propulsion speed as the radius of the tube decreases. We provide some physical insights into how reduced hydrodynamic interactions between moving spheres under confinement may hinder the propulsion of the three-sphere swimmer. We also remark that the reduced propulsion performance stands in stark contrast to the enhanced helical propulsion observed in a capillary tube, highlighting how the manifestation of confinement effects can vary qualitatively depending on the propulsion mechanisms employed by the swimmers.

Chemically reactive MHD peristaltic flow of Jeffrey nanofluid via a vertical porous conduit with complaint walls under the effects of bioconvection and double diffusion

Inspired by significant physiological applications of peristaltic transport, a mathematical model for the peristaltic pumping of a Jeffrey nanofluid containing gyrotactic microorganisms through a flexible and vertical symmetric channel is investigated, along with the effects of thermal radiation, heat source/sink, chemical reaction, porous medium and Hall current. Swimming microorganisms in a model of non-Newtonian fluid has several biological and ecological benefits, including in the pharmaceutical industry, biofertilizers, biofuel technology, biosensors, etc. With these presumptions in mind, a conducting Jeffery fluid flow containing microorganisms via a porous vertical conduit is proposed. The expressions for the flow quantities are established by solving the governing equations of this study analytically using the homotopy perturbation method (HPM). A detailed examination is performed using the tables and graphical representations to comprehend the impact of significant components on this analysis. In addition, the results for Newtonian nanofluid are obtained as a special case and discovered that its velocity is lower than the Jeffrey nanofluid. It is observed that the best velocity distribution can be seen at larger thermal Grashof number and Darcy number. The size of the trapped bolus enhances with the increase of the Hall parameter. Furthermore, the density of the motile microorganism distribution declines for higher bioconvection Peclet number and bioconvection constant.

Nonlinear dynamics and bifurcations of a planar undulating magnetic microswimmer.

Swimming microorganisms such as flagellated bacteria and sperm cells have fascinating locomotion capabilities. Inspired by their natural motion, there is an ongoing effort to develop artificial robotic nanoswimmers for potential in-body biomedical applications. A leading method for actuation of nanoswimmers is by applying a time-varying external magnetic field. Such systems have rich and nonlinear dynamics that call for simple fundamental models. A previous work studied forward motion of a simple two-link model with a passive elastic joint, assuming small-amplitude planar oscillations of the magnetic field about a constant direction. In this work, we found that there exists a faster, backward motion of the swimmer with very rich dynamics. By relaxing the small-amplitude assumption, we analyze the multiplicity of periodic solutions, as well as their bifurcations, symmetry breaking, and stability transitions. We have also found that the net displacement and/or mean swimming speed are maximized for optimal choices of various parameters. Asymptotic calculations are performed for the bifurcation condition and the swimmer's mean speed. The results may enable significantly improving the design aspects of magnetically actuated robotic microswimmers.

Two-dimensional study on the motion and interactions of squirmers under gravity in a vertical channel

We simulated the motions and interactions of circular squirmers under gravity in a two-dimensional channel at finite fluid inertia, aiming to provide a comprehensive analysis of the dynamic features of swimming microorganisms or engineered microswimmers. In addition to a squirmer-type factor (β), another control parameter (α) was introduced, representing ratio of the self-propelling strength to the sedimentation strength of squirmers. Simulations were performed at 0.4 ≤ α ≤ 1.2 and −5 ≤ β ≤ 5. We first considered the sedimentation of a single squirmer. Five patterns were revealed, depending on both α and β: steady downward falling, steady inclined falling or rising and small-scale or large-scale oscillating. Compared with a pusher (β < 0, gaining thrust from rear), a puller (β > 0, gaining thrust from front) is more likely to break down its symmetrical structure and subsequently lose stability, owing to the high-pressure regions on its lateral sides. Typically, a pusher settles faster than a puller, whereas a neutral squirmer (β = 0) settles in between. This is related to the ‘trailing negative flow’ behind a pusher and ‘leading negative flow’ before a puller. We then placed two squirmers in line with the gravity direction to study their interactions. Results show pullers attract each other and come into contact as a result of the low-pressure regions between them, whereas the opposite is observed for pushers. The interactions between two pullers are illustrated by their respective patterns. In contrast, pushers never come into contact and maintain distance from each other with increasing separation. We finally examined how a puller interacts with a pusher.

Bioconvective flow of Maxwell nanofluid with swimming of gyrotactic microorganisms with triple stratification

The article focuses the investigation on Maxwell nanoliquid, under the influence of magnetic field, swimming microorganisms and stratification flow over a vertical stretchy sheet. The physical model is reduced to higher order nonlinear ordinary systems using similarity variables. The homotopy technique has been implemented to solve the ordinary system. The study of heat and mass transfer rate of nanoparticles among with swimming microorganisms is performed employing difference in various parameters and these outcomes are represented using graphs. Relaxation time parameter act as an important role in diminishing velocity profile and the reverse trend found for mixed convection parameter.

Heat and mass transmission in a boundary layer flow due to swimming of motile gyrotactic microorganisms with variable wall temperature over a flat plate

Nanotechnology can significantly revolutionize several industries and technology domains, such as homeland security, food safety, information technology, healthcare, energy, transportation, and environmental research. Thus, a numerical study of boundary layer flow on a moving horizontal flat plate filled with nanofluid with variable temperature at the wall and viscous dissipation in the presence of gyrotactic microorganisms is presented. The partial differential equations governing flow phenomena are transformed into ordinary differential equations with the aid of appropriate similarity transformations. The transformed ordinary differential equations are solved numerically with the help of the built-in BVP4C scheme of MATLAB. After the validation of the scheme, numerical solutions are determined for the temperature, nanoparticle concentration, and motile microorganism profiles, along with physical quantities of interest. The outcomes of physical factors such as the variable temperature index, Prandtl number, Eckert number, Lewis number, Peclet number, plate moving parameter, thermophoresis motion, and Brownian parameters are examined and reported through graphs and tables. From the tables, it is clear that skin friction = 0 when the velocity parameter = 1, which shows that there is no resistance at the fluid-solid surface. It is concluded that by increasing the variable temperature, the temperature gradient rises, because of which the thickness of the thermal boundary layer reduces. Finally, more innovations are inevitable with the advancement of this interdisciplinary science. Moreover, the current investigation may help to efficiently enhance the viscosity, thermal conductivity, thermal diffusivity, and convective heat transmission linked to those base fluids, such as water and oil.

Swimming of gyrotactic micro-organisms within the Williamson blood nano fluid model and solar mimetic system over the peristaltic arterial wall

Swimming of gyrotactic micro-organisms within the Williamson blood nano fluid model and solar mimetic system over the peristaltic arterial wall

Collective Motion and Pattern Formation in Phase-Synchronizing Active Fluids

Many active particles, such as swimming micro-organisms or motor proteins, do work on their environment by going though a periodic sequence of shapes. Interactions between particles can lead to synchronization of their duty cycles. Here, we study the collective dynamics of a suspension of active particles coupled through hydrodynamics. We find that at high enough density the system transitions to a state of collective motion by a mechanism that is distinct from other instabilities in active matter systems. Second, we demonstrate that the emergent nonequilibrium states feature stationary chimera patterns in which synchronized and phase-isotropic regions coexist. Third, we show that in confinement, oscillatory flows and robust unidirectional pumping states exist, and can be selected by choice of alignment boundary conditions. These results point toward a new route to collective motion and pattern formation and could guide the design of new active materials.

Insinuation of Arrhenius Energy and Solar Radiation on Electrical Conducting Williamson Nano Fluids Flow with Swimming Microorganism: Completion of Buongiorno's Model

The enriched thermal mechanisms and progressive of nanomaterial has enthused scientists to give devotion to this area in current days. The versatile and synthesizing utilization of such particles embrace energy production, solar systems, heating and cooling monitoring processes, renewable energy systems, cancer treatments, hybrid-powered motors and Nano electronics. Furthermore, in this era of biotechnology and bioengineering, the bio convection of Nano fluids provides for some enthralling applications, such as enzymes, biosensors and biofuels. With such magnetic applications and attentions. A mathematical model is presented for evaluating the electrical conducting Williamson nano fluid with heat and mass transfer over a porous stretched sheet in the existence of bioconvection. The bioconvection of swimming microorganisms, thermal radiation,thermal conductivity and Arrhenius energy are new facets of this investigation. The higher order non-linear governing partial differential equations (PDEs) are solved by applying appropriate similarity variables and resulting couple of ordinary differential equations (ODEs) is produced. The developing set of ODEs is solved numerically by utilizing well known shooting technique with ND solve command in Wolfram MATHEMATICA and compare the result with pvb4c code in MATLAB. The graphs for different physical quantities of interest together with non-dimension velocity, temperature, concentration and density of micro-organisms profiles are discovered for involving parameters like .magnetic parameter, Brownian motion, Rayleigh number, Peclet number, Bioconvective Lewis number, parameter of thermophoresis and buoyancy ratio parameter. The influence of numerous parameters on flow and heat transfer characteristics are debated.

Entropy analysis on the bioconvective peristaltic flow of gyrotactic microbes in Eyring-Powell nanofluid through an asymmetric channel

The educational value of nanofluids in several industrial and biological sectors, particularly in fluid movement systems known as peristalsis, has piqued researchers' interest in studying the peristaltic movement of nanofluids. Additionally, nanoparticles have crucial roles in many engineering and manufacturing processes, including those involving heat exchangers, cooling systems, boilers, MEMS, chemical engineering, laser diode arrays, and cool automotive engines. Various studies have been conducted on this subject. This is done by looking at how migratory gyrotactic microorganisms migrate through an artery that is anisotropically narrowing in a blood-based nanofluid that is non-Newtonian. To comprehend, the Powell-Eyring fluid model is used how the blood's rheology differs from that of a Newtonian fluid. Both Newtonian fluid characteristics and non-Newtonian traits can be seen in this fluid pattern. Equations for continuity, temperature, motile microbes, momentum, and concentration are used to create the mathematical formulation. The series solutions, which are produced using perturbation theory solutions are discussed using graphs for all dominant parameters. Discussion also includes the distribution of temperature, velocity, and swimming microorganisms. Additionally, the effects of wall shear stress, the Nusselt and Sherwood numbers, as well as the phenomena of trapping, are all examined in detail and shown in the graphs. Entropy generation analyses have also been undertaken. The investigation also reveals a crucial behaviour in the use of the heart-lung engine for extracorporeal blood circulation in medicine that may have an impact on the damage of red blood cells as a result of the large fluctuation in wall shear stress. When liquids are transported using arthro pumps and roller pumps in living organs, the results are likewise of significant use. The results are very helpful for executing particle movements in cardiac surgery and may be applicable to the fluid peristaltic pump used in haemodialysis.

TRP channel responsible for the responses to collision, agitation, and shear in Chlamydomonas.

Swimming microorganisms show various responses to mechanical stimuli. Chlamydomonas cells temporarily swim backward on collision with an obstacle. Beat frequency of cilia increases when agitation is applied by voltexing. Cilia are detached on application of shear with a Dounce-type homogenizer. In this study, we show that a knockout mutant of TRP11, a TRP channel of Chlamydomonas, is defective in all these mechanoresponses. To mimic the mechanical stimulus on collision, we caught a single cell on a glass pipette and tapped the anterior cilia-bearing end of the cell with a micro-glass rod while recording the ciliary motility. On tapping the cell, the bending pattern of cilia changed from the forward mode to the reverse mode. The knockout mutant of TRP11 was deficient in showing this response. The response rarely occurred when the speed of the rod was slower than 100 µm/s, which roughly coincides with the swimming velocity. In addition, the bending pattern conversion hardly occurred when the rod stopped moving 1 µm or more apart from the anterior end of the cell. These findings are consistent with the localization of TRP11 in the proximal region of cilia and the idea that the avoiding reaction on collision is brought about by the activation of TRP11 through the deformation of the proximal region of cilia. TRP11 structure predicted by AlphaFold2 shows conservation of the typical TRP channel structure including pre-S1, S1-S4, S4-S5 linker, S5-pore helix-S6, and TRP helix, while bearing long but poorly resolved sequences of extracellular S1-S2 linker and intracellular C-terminal region.

Gyrotactic micro-organisms swimming under the Hyperbolic Tangent Blood Nano Material and Solar biomimetic system over the Esophagus

Gyrotactic micro-organisms swimming under the Hyperbolic Tangent Blood Nano Material and Solar biomimetic system over the Esophagus