Suspension Of Gyrotactic Microorganisms Research Articles

Bioconvection on Non-Newtonian Magnetohydrodynamics Carreau Nanofluid with Activation Energy and Binary Chemical Reaction in Darcy Forchhiemer Porous Medium

In this present research, suspensions of gyrotactic micro-organisms on non-newtonian carreau nanofluid with activation energy and binary chemical reaction is examined which is implanted under Darcy Forchhiemer porous medium. Similarity transformations are used to convert the governing equation into a highly nonlinear ODE’s. Fifth-order Runge Kutta-Fehlberg method using shooting technique is utilized to solve ODE’s. Velocity, temperature, concentration, and density of motile gyrotactic microorganisms profile were depicted graphically and explained briefly. It is observed that activation energy enhances the concentration profile of both pseudoplastic and dilatant fluids. Present results is compared with previously published work which is found to be in good agreement.

STABILITY ANALYSIS OF BIOCONVECTIVE HEAT TRANSFER IN A SUSPENSION OF GYROTACTIC MICROORGANISMS UNDER VERTICAL VIBRATION

Vertical vibration is an important technique to reduce or increase the bioconvective heat transfer. It has great applications in biotechnology, biomedicine, enhancing oil recovery, mixing in microvolumes, analysis of whole body vibration (WBV), and industry. The present study aims to investigate the influence of vertical vibration on the initiation of thermo-bioconvection in a suspension of randomly swimming gyrotactic microorganisms in a shallow thermally stratified horizontal fluid layer. The time-averaged method, linear stability analysis, and single-term Galerkin technique with different boundary layers are employed on the set of field equations. A secular equation is obtained in terms of vibrational and bioconvectional parameters for rigid-rigid and rigid-free boundary conditions. The analysis reported that vertical vibration destabilizes the suspension due to randomly swimming of gyrotactic microorganisms, i.e., enhancing the rate of bioconvective heat transfer. The authors also found that pertinent controlling parameters influence the size of the cell of vibrational thermo-bioconvection. It is observed that the diffusion and average volume of randomly swimming microorganisms affect the bioconvective heat transfer of the vibrational system inversely.

Entropy generation optimization in an unsteady hybrid nanofluid flow between two rotating disks: a numerical bioconvection model

In the context of bioconvection, bacteria are swimming microorganisms. Actually, a microorganism’s species is related to a focused swimming cell in the convection model. Unsteady chemically reactive (Water–Copper ()–Ferrous Oxide ()) hybrid nanofluid dynamics between two stretchable rotating disks at varied Lorentz force and viscous dissipation are unknown when the suspension of gyrotactic micro-organisms is taken into account. The paper’s novelty is addressing this gap, which is to examine the impact of chemical reactions on the unsteady bioconvective hybrid nanofluid flow between two stretchable rotating disks with viscous dissipation and the magnetic field. The use of Von-Karman similarity transformations allows for the conversion of governing equations into nonlinear ordinary differential equations. Based on the combination of Runge–Kutta fourth order and shooting methods, the final equations are calculated. A major finding of this study is Reynolds number escalates both axial and radial velocities but decreases the tangential velocity. The temperature increases with the rise in both Eckert number and heat source parameters. The concentration decreases with the rise in Schmidt number and chemical reaction parameter.

Dual solution for double-diffusive mixed convection opposing flow through a vertical cylinder saturated in a Darcy porous media containing gyrotactic microorganisms

The steady mixed convection flow towards an isothermal permeable vertical cylinder nested in a fluid-saturated porous medium is studied. The Darcy model is applied to observe bioconvection through porous media. The suspension of gyrotactic microorganisms is considered for various applications in bioconvection. Appropriate similarity variables are opted to attain the dimensionless form of governing equations. The resulting momentum, energy, concentration, and motile microorganism density equations are then solved numerically. The resulting dual solutions are graphically visualized and physically analyzed. The results indicate that depending on the systems' parameters, dual solutions exist in opposing flow beyond a critical point where both solutions are connected. Our results were also compared with existing literature.

Nonlinear mixed convective Williamson nanofluid flow with the suspension of gyrotactic microorganisms

This investigation aims to present the thermally developed bioconvection flow of Williamson nanoliquid over an inclined stretching cylinder in presence of linear mixed convection and nonuniform heat source/sink. The activation energy and suspension of gyrotactic microorganisms are accounted with applications of bioconvection phenomenon. Appropriate nondimensional variables are opted to attain the dimensionless form of flow equations. The resulting momentum, energy, concentration and motile density equations are abridged to highly coupled and nonlinear in nature. The numerical treatment is followed for the solution procedure by employing the shooting method. The influence of some relevant dimensionless parameters is discoursed graphically along with physical justifications. Moreover, the impact of several dimensionless parameters on skin friction and Nusselt number is obtained and listed in tables. It is observed that the velocity of fluid shows a decreasing variation for Williamson fluid parameter. The change in unsteadiness parameter and heat source parameter enhanced the nanofluid temperature. The motile microorganisms profile declines with bioconvection constant and bio-convection Lewis number.

Double-Diffusive Bioconvection in a Suspension of Gyrotactic Microorganisms Saturated by Nanofluid

Double-Diffusive Bioconvection in a Suspension of Gyrotactic Microorganisms Saturated by Nanofluid

Linear stability of thermal-bioconvection in a suspension of gyrotactic micro-organisms

By utilizing a randomly swimming model, a linear stability analysis is applied to investigate the stability of bioconvection in a horizontal suspension layer of motile gyrotactic micro-organisms with heated from below. The micro-organisms under consideration are orientated by a balance between a gravitational torque, due to them being bottom heavy, and viscous torque arising from local fluid velocity gradients. The obtained eigenvalue problem containing thermal Rayleigh number and bioconvection Rayleigh number is solved numerically using one-term Galerkin method. The case of non-oscillatory instability is analyzed, the relationship among thermal Rayleigh number, bioconvection Rayleigh number, Lewis number, critical wavenumber and the shape of microorganisms are discussed. We point out that the heating from below makes the layer more unstable. When increasing the value of thermal Rayleigh number to 1750, the suspension becomes unstable itself, which imply that bioconvection Rayleigh number has nothing to do with the stability of this system. We also find that Lewis number has no effect on critical value of thermal Rayleigh number, but has a great influence on critical bioconvection Rayleigh number. The increasing cell eccentricity enlarges the critical value of bioconvection Rayleigh number, which means that the suspension is more stable.

3D Casson nanofluid flow over slendering surface in a suspension of gyrotactic microorganisms with Cattaneo-Christov heat flux

A mathematical model is proposed to execute the features of the non-uniform heat source or sink in the chemically reacting magnetohydrodynamic (MHD) Casson fluid across a slendering sheet in the presence of microorganisms and Cattaneo-Christov heat flux. Multiple slips (diffusion, thermal, and momentum slips) are applied in the modeling of the heat and mass transport processes. The Runge-Kutta based shooting method is used to find the solutions. Numerical simulation is carried out for various values of the physical constraints when the Casson index parameter is positive, negative, or infinite with the aid of plots. The coefficients of the skin factors, the local Nusselt number, and the Sherwood number are estimated for different parameters, and discussed for engineering interest. It is found that the gyrotactic microorganisms are greatly encouraged when the dimensionless parameters increase, especially when the Casson fluid parameter is negative. It is worth mentioning that the velocity profiles when the Casson fluid parameter is positive are higher than those when the Casson fluid parameter is negative or infinite, whereas the temperature and concentration fields show exactly opposite phenomena.

Darcy–Brinkman bio-thermal convection in a suspension of gyrotactic microorganisms in a porous medium

On the basis of Darcy–Brinkman model, linear stability analysis is used to study bio-thermal convection in a suspension of gyrotactic microorganisms in a highly porous medium heated from below. A Galerkin method is performed to solve the governing equations generating a correlation between the traditional thermal Rayleigh number and the critical value of the bioconvection Rayleigh number. The effects of three variables including the bioconvection Peclet number, the gyrotaxis number and the modified Darcy number on both the wave number and the critical bioconvection Rayleigh number are analyzed and shown graphically. Results indicate that the critical bioconvection Rayleigh number becomes larger with increasing Darcy number.

Magnetic field analysis in a suspension of gyrotactic microorganisms and nanoparticles over a stretching surface

The combine effects of magnetic field bioconvection, Brownian motion and thermophoresis on a free convection nanofluid flow over a stretching sheet containing gyrotactic microorganisms are investigated. The self-similar Buongiorno model is analyzed first time for stretching sheet numerically. The present results are compared with available data and are found in an excellent agreement. Pertinent results are presented graphically and discussed quantitatively with respect to variation in bioconvection parameters.

The onset of bio‐thermal convection in a suspension of gyrotactic microorganisms in a fluid layer with an inclined temperature gradient

PurposeThe purpose of this paper is to investigate a combined bioconvection and thermal instability problem in a horizontal layer of finite depth with a basic temperature gradient inclined to the vertical. The basic flow, driven by the horizontal component of temperature gradient, is the Hadley circulation, which becomes unstable when the vertical temperature difference and density stratification induced by upswimming of microorganisms that are heavier than water become sufficiently large.Design/methodology/approachLinear stability analysis of the basic state is performed; the numerical problem is solved using the collocation method.FindingsThe steady‐state solution of this problem is obtained. Linear stability analysis of this steady‐state solution for the case of three‐dimensional disturbances is performed; the numerical problem is solved using the collocation method. The stability problem is governed by three Rayleigh numbers: the bioconvection Rayleigh number and two thermal Rayleigh numbers characterizing temperature gradients in the vertical and horizontal directions, respectively.Research limitations/implicationsFurther research should address the application of weakly non‐linear analysis to this problem.Practical implicationsThe dependence of the critical bioconvection Rayleigh number on the two thermal Rayleigh numbers and other relevant parameters is investigated.Originality/valueThis paper presents what is believed to be the first research dealing with the effect of inclined temperature gradient on the stability of bioconvection in a suspension of gyrotactic microorganisms.

The Onset of Convection in a Suspension of Gyrotactic Microorganisms in Superimposed Fluid and Porous Layers: Effect of Vertical Throughflow

The purpose of this paper is to investigate the effect of vertical throughflow on the onset of bioconvection in a suspension of gyrotactic microorganisms. A dilute suspension of gyrotactic microorganisms in a shallow system that consists of superimposed fluid and porous layers is considered. A linear instability analysis of this problem is performed and the Galerkin method is utilized to solve the eigenvalue problem. The analysis leads to an equation for the critical Rayleigh number. It is shown that the vertical throughflow stabilizes the system.

The onset of bio-thermal convection in a suspension of gyrotactic microorganisms in a fluid layer: Oscillatory convection

A linear stability analysis is applied to investigate the onset of bioconvection in a horizontal layer of fluid containing a suspension of motile microorganisms with heating or cooling from below. With cooling from below the stabilizing effect of the thermal stratification is opposed to the destabilizing effect resulting from the congregation of the microorganisms, and oscillatory convection is possible in certain circumstances. The stability criterion is found in terms of a thermal Rayleigh number, a bioconvection Rayleigh number, a bioconvection Péclet number, a gyrotactic number, and a measure of the cell eccentricity, together with (in the case of oscillatory convection) a Prandtl number and a Lewis number.

The onset of bioconvection in a suspension of gyrotactic microorganisms in a fluid layer of finite depth heated from below

The aim of this paper is to investigate the effect of heating from below on the stability of a suspension of motile gyrotactic microorganisms in a fluid layer of finite depth. This problem is relevant to a number of geophysical applications, such as investigation of the dynamics of some species of thermophiles (heat-loving microorganisms) living in hot springs. It is established that heating from below makes the system more unstable and helps the development of bioconvection. By performing a linear stability analysis, a correlation for the critical bioconvection Rayleigh number is obtained.

Effect of small particles on this stability of bioconvection in a suspension of gyrotactic microorganisms in a layer of finite depth

We investigate the effect of small particles that are heavier than water on the stability of a suspension of motile gyrotactic microorganisms in a horizontal fluid layer of finite depth. If bioconvection develops, it enhances mixing and slows down the settling of the particles, which may be important in pharmaceutical applications. A linear stability analysis is utilized to investigate this problem. It is established that the critical Rayleigh number increases with the increase of the average number density of small particles, which means that the particles make the suspension more stable

Growth of bioconvection patterns in a suspension of gyrotactic micro-organisms in a layer of finite depth

The effect of gyrotaxis on the linear stability of a suspension of swimming, negatively buoyant micro-organisms is examined for a layer of finite depth. In the steady basic state there is no bulk fluid motion, and the upwards swimming of the cells is balanced by diffusion resulting from randomness in their shape, orientation and swimming behaviour. This leads to a bulk density stratification with denser fluid on top. The theory is based on the continuum model of Pedley, Hill & Kessler (1988), and employs both asymptotic and numerical analysis. The suspension is characterized by five dimensionless parameters: a Rayleigh number, a Schmidt number, a layer-depth parameter, a gyrotaxis number G, and a geometrical parameter measuring the ellipticity of the micro-organisms. For small values of G, the most unstable mode has a vanishing wavenumber, but for sufficiently large values of G, the predicted initial wavelength is finite, in agreement with experiments. The suspension becomes less stable as the layer depth is increased. Indeed, if the layer is sufficiently deep an initially homogeneous suspension is unstable, and the equilibrium state does not form. The theory of Pedley, Hill & Kessler (1988) for infinite depth is shown to be appropriate in that case. An unusual feature of the model is the existence of overstable or oscillatory modes which are driven by the gyrotactic response of the micro-organisms to the shear at the rigid boundaries of the layer. These modes occur at parameter values which could be realized in experiments.