Swimming Microorganisms Research Articles

Marangoni‐bioconvectional flow of Reiner–Philippoff nanofluid with melting phenomenon and nonuniform heat source/sink in the presence of a swimming microorganisms

The nanofluids are more practical to enhance the heat transfer compared to regular fluids. Such effectiveness in mind causes this communication's concern to investigate the Darcy–Forchheimer flow of Reiner–Philippoff nanofluid with heat source/sink, thermal conductivity in the occurrence of motile microorganisms over the stretching surface. The melting phenomenon is also considered. For this purpose, the set of nonlinear partial differential equation (PDE) is converted into ordinary differential equation (ODE) using the required translation of similarities. These obtained simple ordinary differential equations are solved using the built‐in MATLAB computational tool bvp4c method. The graphical outcomes are delineated for velocity, temperature, concentration, and motile microorganisms profiles via Lewis number, fluid parameter, radiation parameter, thermophoresis parameter, Brownian motion parameter, Prandtl number, bioconvection Lewis number, Reynolds number, Peclet number, and bioconvection Rayleigh number, respectively. The numerical data confirm that the coefficient of wall heat transfer reduces for the greater values of the Schmidt number and thermophoresis parameter. The heat profile is reduced for the higher magnitude of the Prandtl number while boosted up for the higher estimations of thermal radiation parameter. The mass transfer of microorganisms is boosted via the Peclet and bioconvection Lewis number.

Phyllobacterium calauticae sp. nov. isolated from a microaerophilic veil transversed by cable bacteria in freshwater sediment.

Microaerophilic veils of swimming microorganisms form at oxic-anoxic interfaces, mostly described in sediments where sulfide from below meets oxygen diffusing in from the water phase. However, microaerophilic veils form even when these gradients do not overlap, for example when cable bacteria activity leads to a suboxic zone. This suggests that veil microorganisms can use electron donors other than sulfide. Here we describe the extraction of microorganisms from a microaerophilic veil that formed in cable-bacteria-enriched freshwater sediment using a glass capillary, and the subsequent isolation of a motile, microaerophilic, organoheterotrophic bacterium, strain R2-JLT, unable to oxidize sulfide. Based on phenotypic, phylogenetic, and genomic comparison, we propose strain R2-JLT as a novel Phyllobacterium species, P. calauticae sp. nov.. The type strain is R2-JLT (= LMG 32286T = DSM 112555T). This novel isolate confirms that a wider variety of electron donors, including organic compounds, can fuel the activity of microorganisms in microaerophilic veils.

Zero and Nonzero Mass Flux Effects of Bioconvective Viscoelastic Nanofluid over a 3D Riga Surface with the Swimming of Gyrotactic Microorganisms

This work addresses 3D bioconvective viscoelastic nanofluid flow across a heated Riga surface with nonlinear radiation, swimming microorganisms, and nanoparticles. The nanoparticles are tested with zero (passive) and nonzero (active) mass flux states along with the effect of thermophoresis and Brownian motion. The physical system is visualized via high linearity PDE systems and nondimensionalized to high linearity ordinary differential systems. The converted ordinary differential systems are solved with the aid of the homotopy analytic method (HAM). Several valuable and appropriate characteristics of related profiles are presented graphically and discussed in detail. Results of interest such as the modified Hartmann number, mixed convection parameter, bioconvection Rayleigh number, and Brownian motion parameter are discussed in terms of various profiles. The numerical coding is validated with earlier reports, and excellent agreement is observed. The microorganisms are utilized to improve the thermal conductivity of nanofluid, and this mechanism has more utilization in the oil refinery process.

Bidirectional non-linear stretched flow of Williamson nanofluid with swimming of motile gyrotactic microorganisms

The fields of material manufacture, graphic designing, information science, aerodynamics, plastic industry and biotechnology have been found to have a greater reliance on the phenomenon of fluid flow over three-dimensional realms. Consequently, this article has been focused to the study of Williamson nanofluid containing microorganisms over three-dimensional surface under the influence of magnetic field through bidirectional non-linearly stretched surface. To transform the set of nonlinear partial differential equations into ordinary differentials equations by using appropriate similarity transformation. These obtained fundamental ordinary differential equations are solved numerically by exploiting bvp4c process built-in MATLAB mathematical software. The presentation of the results has been made in form of graphs and tables to warrant the comparison between different scenarios. More specifically the parameters like temperature profile, velocity profile, motility of organisms, concentration profiles, Peclet numbers, Lewis number, Williamson parameters, material parameter, Brownian motion parameters, Rayleigh numbers and Prandtl number were presented as the graphical outcomes. The numerical data suggested that greater values of Schmidt number, thermophoresis parameters and Brownian motion reduce the coefficient of wall heat transfer. The study has its applications in transportation hypothesis that is utilized in many automotive and industrial processes. The field of industrial manufacturing has also many applications that consider flow over a bidirectional stretched surface. The current approach explores the cumulative effect of different physical features on the flow of Williamson fluid, and there is no such effort in the reviewed studies.

Numerical simulation for bioconvectional flow of burger nanofluid with effects of activation energy and exponential heat source/sink over an inclined wall under the swimming microorganisms

Nanofluids has broad applications such as emulsions, nuclear fuel slurries, molten plastics, extrusion of polymeric fluids, food stuffs, personal care products, shampoos, pharmaceutical industries, soaps, condensed milk, molten plastics. A nanofluid is a combination of a normal liquid component and tiny-solid particles, in which the nanomaterials are immersed in the liquid. The dispersion of solid particles into yet another host fluid will extremely increase the heat capacity of the nanoliquid, and an increase of heat efficiency can play a significant role in boosting the rate of heat transfer of the host liquid. The current article discloses the impact of Arrhenius activation energy in the bioconvective flow of Burger nanofluid by an inclined wall. The heat transfer mechanism of Burger nanofluid is analyzed through the nonlinear thermal radiation effect. The Brownian dispersion and thermophoresis diffusions effects are also scrutinized. A system of partial differential equations are converted into ordinary differential equation ODEs by using similarity transformation. The multi order ordinary differential equations are reduced to first order differential equations by applying well known shooting algorithm then numerical results of ordinary equations are computed with the help of bvp4c built-in function Matlab. Trends with significant parameters via the flow of fluid, thermal, and solutal fields of species and the area of microorganisms are controlled. The numerical results for the current analysis are seen in the tables. The temperature distribution increases by rising the temperature ratio parameter while diminishes for a higher magnitude of Prandtl number. Furthermore temperature-dependent heat source parameter increases the temperature of fluid. Concentration of nanoparticles is an decreasing function of Lewis number. The microorganisms profile decay by an augmentation in the approximation of both parameter Peclet number and bioconvection Lewis number.

Nonlinear magnetohydrodynamic flow of nanofluids across a porous matrix over an extending sheet with mass transpiration and bioconvection

AbstractThe consequences of the nonlinear magnetic field and radiative thermal energy are evaluated for bioconvective viscous flow across a porous matrix over a nonlinearly stretching sheet. The rationale of the study is to attain enhanced thermal transportation. The dilute dispersion of nanoentities and bioconvection of swimming microorganisms are taken into consideration. The coupled partial differential system of field equations is transformed into ordinary differential form. Finally, the numeric solution is obtained by utilizing the fourth‐order Runge–Kutta method shooting technique, and results are validated through an acceptable accord with existing studies. The variation of influential parameters such as combined magnetic parameter, mass transpiration parameter, thermophoresis, Brownian motion, bioconvection Lewis numbers made notable impacts on fluid velocity, temperature, concentration of nanoentities, and distribution of microorganisms.

Bioconvection mechanism using third-grade nanofluid flow with Cattaneo–Christov heat flux model and Arrhenius kinetics

This paper aims to study the effects of activation energy and thermal radiation in the bioconvection flow of nanofluid (third-grade nanofluid) containing swimming microorganisms in the presence of a heat source-sink past a stretching sheet. Brownian movement and thermophoresis diffusion are used in mathematical modeling. The given flow phenomenon is modeled in the form of governing partial differential equations. Furthermore, appropriate dimensionless transformation is used to transfer the governing system of PDEs into an ordinary one. The remodeled systems of ODEs are tackled numerically by bvp4c on Matlab with a shooting scheme in computational tool MATLAB. The bearing of prominently involved parameters on the numerical solution of velocity, temperature distribution, nanoparticles concentration and concentration of microorganisms is comprehensively discussed and elaborated through figures. It is established that velocity can be improved with a mixed convection aspect. Furthermore, the temperature and concentration of nanoparticles reduce against Prandtl number, also, large Peclet number declines the microorganisms field. The work contained in this paper has applications in nanotechnology, electrical and mechanical engineering, biomedicine, biotechnology, drug delivery, cancer treatment, food processing and various industries. No such work is yet reported, and it is good for the research in applied sciences.

Dynamics of water conveying SWCNT nanoparticles and swimming microorganisms over a Riga plate subject to heat source/sink

Electromagnetohydrodynamic (EMHD) is very important because of its numerous advantages such as flow control in fluidics networks, fluid pumping, thermal reactors, mixing, fluid stirring, liquid chromatography, and micro coolers. Based on the above applications in this article discussed the electromagnetic forces on the SWCNT/water flow with microorganisms over a Riga plate subject to slip effects. In addition, the uniform heat source/sink effect is used in the energy equation, as well as the thermophoretic effect in the concentration equation. The governing nonlinear system of partial differential equations (PDEs) was reduced to ordinary differential equations (ODEs) by applying the appropriate similarity variables. Hence, Runge-Kutta-Fehlberg (RKF-45) method was applied to numerically solve the extremely nonlinear system. Based on the analysis of the results, it is worth concluding that raising the role of slip effects lowers the velocity, temperature, and concentration curves, while increasing the solid volume fraction increases the temperature, concentration, and motile microorganism density.

MHD nanofluid flow over stretching cylinder with convective boundary conditions and Nield conditions in the presence of gyrotactic swimming microorganism: A biomathematical model

In current mathematical configuration, the self-propelled movement of gyrotactic swimming microorganisms in the generalized slip flow of MHD nanoliquid past a stretching cylinder is discussed. Convective heat transfer is assumed along with Nield conditions on boundary. The formulation of this biomathematical model yields the boundary value problem of nonlinear partial differential equations. First, modelled mathematical system is transferred into non-dimensional form with the aid of suitable scaling variables and then shooting technique (along with Runge-Kutta-Fehlberg (R-K-F) method) is applied to obtain numerical solution of governing system. The computed numerical solutions are presented with figures and tables, and then these results are critically analyzed in both quantitative and qualitative manners.

Numerical performance of thermal conductivity in Bioconvection flow of cross nanofluid containing swimming microorganisms over a cylinder with melting phenomenon

This study investigates the effects of melting phenomena and non-linear thermal radiation in Cross nanofluid bioconvection flow with motile microorganisms with a convective boundary over a cylinder. Brownian motion and thermophoresis diffusion are also taken into account in this mathematical model. A governing partial differential equation is used to represent the given flow phenomena. The proper dimensionless transformation is then employed to convert the PDE controlling system into an ordinary one. Bvp4c numerically solves redesigned ODE problems using a shooting strategy in the computational tool MATLAB. Figures versus velocity, temperature distribution, nanoparticle concentration, and microbe concentration profiles are used to analyze and expound on the notably involved aspects thoroughly. It has been demonstrated that increasing the estimates of a mixed convection parameter can enhance velocity. By increasing the Prandtl number, the temperature and concentration of nanoparticles decrease. A high Peclet value lowers the microorganism's profile.

Microgel that swims to the beat of light

Complementary to the quickly advancing understanding of the swimming of microorganisms, we demonstrate rather simple design principles for systems that can mimic swimming by body shape deformation. For this purpose, we developed a microswimmer that could be actuated and controlled by fast temperature changes through pulsed infrared light irradiation. The construction of the microswimmer has the following features: (i) it is a bilayer ribbon with a length of 80 or 120 upmu m, consisting of a thermo-responsive hydrogel of poly-N-isopropylamide coated with a 2-nm layer of gold and equipped with homogeneously dispersed gold nanorods; (ii) the width of the ribbon is linearly tapered with a wider end of 5 upmu m and a tip of 0.5 upmu m; (iii) a thickness of only 1 and 2 upmu m that ensures a maximum variation of the cross section of the ribbon along its length from square to rectangular. These wedge-shaped ribbons form conical helices when the hydrogel is swollen in cold water and extend to a filament-like object when the temperature is raised above the volume phase transition of the hydrogel at 32,^{circ } hbox {C}. The two ends of these ribbons undergo different but coupled modes of motion upon fast temperature cycling through plasmonic heating of the gel-objects from inside. Proper choice of the IR-light pulse sequence caused the ribbons to move at a rate of 6 body length/s (500 upmu m/s) with the wider end ahead. Within the confinement of rectangular container of 30 upmu m height and 300 upmu m width, the different modes can be actuated in a way that the movement is directed by the energy input between spinning on the spot and fast forward locomotion.Graphic abstract

Mechanical rotation at low Reynolds number via reinforcement learning

There is growing interest in the development of artificial microscopic machines that can perform complex maneuvers like swimming microorganisms for potential biomedical applications. At the microscopic scales, the dominance of viscous over inertial forces imposes stringent constraints on locomotion. In the absence of inertia, Purcell first proposed an elegant way to generate net translation using kinematically irreversible motions [E. M. Purcell, “Life at low Reynolds number,” Am. J. Phys. 45, 3–11 (1977)]. In addition to net translation, a more recent prototype known as Purcell's “rotator” has been proposed in Dreyfus et al. [“Purcell's “rotator”: Mechanical rotation at low Reynolds number,” Eur. Phys. J. B 47, 161–164 (2005)] as a mechanical implementation of net rotation at low Reynolds numbers. These ingenious designs rely on knowledge of the surrounding environment and the physics of locomotion within the environment, which may be incomplete or unclear in more complex scenarios. More recently, reinforcement learning has been used as an alternative approach to enable a machine to learn effective locomotory gaits for net translation based on its interaction with the surroundings. In this work, we demonstrate the use of reinforcement learning to generate net mechanical rotation at low Reynolds numbers without requiring prior knowledge of locomotion. For a three-sphere configuration, the reinforcement learning recovers the strategy proposed by Dreyfus et al. As the number of spheres increases, multiple effective rotational strategies emerge from the learning process. However, given sufficiently long learning processes, all machines considered in this work converge to a single type of rotational policies that consist of traveling waves of actuation, suggesting its optimality of the strategy in generating net rotation at low Reynolds numbers.

Second-order slip effect on bio-convectional viscoelastic nanofluid flow through a stretching cylinder with swimming microorganisms and melting phenomenon

The uses of nanofluid in cooling technology is growing. The nanofluid is made up of metallic and nonmetallic particles that are distributed in a base fluid. This research provides a summary of fuel cell models, uses, and how they function. Researchers have made significant contributions in the following era due to the importance of bioconvection in nanotechnology and a variety of biological systems. The idea of the recent work is to evaluate the aspects of the Cattaneo–Christov (C–C) heat and mass flux model, the second-order boundary with melting phenomenon on the bioconvective flow of viscoelastic nanofluid across a cylinder. The nature of the activation energy, thermal conductivity is also taken into account. Appropriate similarity transformations are utilized to reframe the PDEs of the modeled system into a system of ODEs. The governing equations for the renovated system of ODEs are treated by a shooting function. Here bvp4c built-in function computational tool MATLAB is used. The two-dimensional flow has ceased application in several areas, such as polymer industry, material synthesis technology, nano-biopolymer computer graphics processing, industry, mechanical engineering, airplane structures, and scientific research, which is much more useful in nanotechnology. The results of emerging important flow-field parameters are investigated with the aid of graphs and numerical results.

Numerical simulation for bio-convective flow of Sutterby nanofluid by a rotating disk

Nanofluids play a vital role in the improvement of our practical life. The potential usage of nanomaterials in different applications such as oil recovery, refrigeration systems, a freeze of electrical components in computers, development of liquid displays, cooling spirals, mechanical engineering, electrical engineering, heat storage devices and biotechnology. Swimming microorganisms have a crucial role in various areas of life, such as medicines, bioengineering, biofuels and food processing. Microorganisms are used as antibiotics in medicine and help to create a vaccine. Keeping in mind these applications, the current research provides a mathematical model for bioconvection Sutterby nanofluid flowing past the rotating stretching disk with magnetic field, motile microorganisms, chemical reactions and heat generation. The Brownian movement and thermophoresis diffusions are also considered. The governing equation structures are simplified by suitable transformations. A popular bvp4c solver in MATLAB computational software is employed to achieve numerical results for the non-linear model. The flow evaluation for the effects of several prominent numbers on temperature, velocities, concentration and motile microorganism profiles is executed graphically and numerically. The volumetric concentration of nanomaterial rises for thermophoresis number while shows opposite nature for Prandtl and Lewis parameters. The boosting values of bioconvection Lewis number, Peclet number and bioconvection Rayleigh number decay the motile microorganisms’ concentration.

A three-dimensional bioconvection Williamson nanofluid flow over bidirectional accelerated surface with activation energy and heat generation

The main focus of this research is to explore the consequences of motile gyrotactic microorganisms for unsteady Williamson nanofluid induced by bidirectional periodically accelerated surface. The combined features of magnetic and buoyancy forces with association of nanoparticles and swimming microorganisms developed the nanofluid bioconvection. Thermal radiation and heat generation aspects are considered to analyze the heat transportation phenomenon. The consequences of activation energy and chemical reaction are further explored for physical relevance. Appropriate transformations have been employed to transmute the formulated nonlinear equations into dimensionless form, and then analytically elucidated by homotopic technique. The effect of diverse dominant parameters on velocities, concentration, temperature, motile microorganisms as well as skin friction coefficients are deliberated through various graphs while the deviation in local Sherwood, Nusselt and motile density numbers have been deliberated by numerical data in tabular form. It is noticed that both velocity components periodically drop for augmentation in Williamson parameter. Current investigation accentuated that higher reaction rate leads to decay in concentration distribution, but impact of activation energy parameter is rather conflicting. Furthermore, the profile of motile microorganism leads to be intensified for higher magnetic parameter, while opposite trend is perceived for bioconvected Peclet and Lewis numbers.

Analysis of Buongiorno’s nanofluid model in marangoni convective flow with gyrotactic microorganism and activation energy

This communication is to analyze the Marangoni convection MHD flow of nanofluid. Marangoni convection is very useful physical phenomena in presence of microgravity conditions which is generated by gradient of surface tension at interface. We have also studied the swimming of migratory gyrotactic microorganisms in nanofluid. Flow is due to rotation of disk. Heat and mass transfer equations are examined in detail in the presence of heat source sink and Joule heating. Nonlinear mixed convection effect is inserted in momentum equation. Appropriate transformations are applied to find system of equation. HAM technique is used for convergence of equations. Radial and axial velocities, concentration, temperature, motile microorganism profile, Nusselt number and Sherwood number are sketched against important parameters. Marangoni ratio parameter and Marangoni number are increasing functions of axial and radial velocities. Temperature rises for Marangoni number and heat source sink parameter. Activation energy and chemical reaction rate parameter have opposite impact on concentration profile. Motile density profile decays via Peclet number and Schmidt number. Magnitude of Nusselt number enhances via Marangoni ratio parameter.

Magnetohydrodynamic bioconvection of oxytactic microorganisms in porous media saturated with Cu–water nanofluid

Purpose The purpose of this study is to address magnetohydrodynamic (MHD) bioconvection caused by the swimming of oxytactic microorganisms in a linearly heated square cavity filled with porous media and Cu–water nanofluid. The effects of different multiphysical aspects are demonstrated using local distributions as well as global quantities for fluid flow, temperature, oxygen concentration and microorganisms population. Design/methodology/approach The coupled transport equations are converted into the nondimensional partial differential equations, which are solved numerically using a finite volume-based computing code. The flow of Cu–water nanofluid through the pores of porous media is formulated following the Brinkman–Forchheimer–Darcy model. The swimming of oxytactic microorganisms is handled following a continuum model. Findings The analysis of transport phenomena of bioconvection is performed in a linearly heated porous enclosure containing Cu–water nanofluid and oxytactic microorganisms under the influence of magnetic fields. The application of such a system could have potential impacts in diverse fields of engineering and science. The results show that the flow and temperature distribution along with the isoconcentrations of oxygen and microorganisms is markedly affected by the involved governing parameters. Research limitations/implications Similar study of bioconvection could be extended further considering thermal radiation, chemical attraction, gravity and light. Practical implications The outcomes of this investigation could be used in diverse fields of multiphysical applications, such as in food industries, chemical processing equipment, fuel cell technology and enhanced oil recovery. Originality/value The insight of the linear heating profile reveals a special attribute of simultaneous heating and cooling zones along the heated side. With such an interesting feature, the MHD bioconvection of oxytactic microorganisms in nanofluid-filled porous substance is not reported so far.

Numerical simulation of squeezing flow Jeffrey nanofluid confined by two parallel disks with the help of chemical reaction: effects of activation energy and microorganisms

Abstract The utilization of nano-materials in a base fluid is a new dynamic technique to improve the thermal conductivity of base fluids. The suspension of tiny nanoparticles in base fluids is referred to the nano-materials. Nanofluids play a beneficial contribution in the field of nanotechnology, heat treatment enhancement, cooling facilities, biomedicine, bioengineering, radiation therapy and in military fields. The analysis of bioconvection characteristics for unsteady squeezing flow of non-Newtonian Jeffery nanofluid with swimming microorganisms over parallel disks with thermal radiation and activation energy has been studied in this continuation. The motivations for performing current analysis are to inspect the heat transfer enhancement in Jeffrey nanofluid in presence of multiple thermal features. The Jeffrey nanofluid contains motile microorganisms which convey dynamic applications in bio-technology and medical sciences and agricultural engineering. The system comprising differential equations of derivative is restricted to an ordinary one by means of a sufficient dimensionless similarity vector, and then implemented numerically by means of a famous shooting scheme with MATLAB tools. The effect of the significant parameters over the fluid flow is investigated from a physical point of view. The numerical findings of the modeled system are explored in detail using tabular data.

Swimming of microorganisms in quasi-two-dimensional membranes

Abstract

Hydrodynamic interactions between swimming microorganisms in a linearly density stratified fluid.

Oceans and lakes sustain intense biological activity due to the motion of marine organisms, which has significant ecological and environmental impacts. The motion of individual organisms and their interactions with each other play a significant role in the collective motion of swimming organisms. However, ubiquitous vertical density stratification in these aquatic environments significantly alters the swimmer interactions as compared to in a homogeneous fluid. Furthermore, organisms have sizes varying over a wide range which results in finite inertia. To this end, we numerically investigate the interactions between a pair of model swimming organisms in two configurations: (1) approaching each other and (2) moving side by side with finite inertia in a linearly density stratified fluid. We use the archetypal reduced-order squirmer model to numerically model the swimming organisms. We present trajectories and the contact times of interacting squirmer (puller & pusher) pairs for different Re in the range 1-50 and Ri in the range 0-10. Depending on the squirmer Re and Ri we observe that the squirmer interactions can be categorized as (i) pullers getting trapped in circular loops at high Re and low Ri, (ii) pullers escaping each other with separating angle decreasing with increasing stratification at low Re and high Ri, (iii) pushers sticking to each other after the collision and deflecting away from the collision plane for either low Re or high Ri, (iv) pushers escaping otherwise with an angle of separation increasing with stratification. Stratification also increases the contact time for squirmer pairs. The presented results can be useful to understand the mechanisms behind the accumulation of planktonic organisms in horizontal layers in a stratified environment such as oceans and lakes.