Showing papers by "Oluwole Daniel Makinde published in 2020"

Impact of Entropy Generation and Nonlinear Thermal Radiation on Darcy–Forchheimer Flow of MnFe2O4-Casson/Water Nanofluid due to a Rotating Disk: Application to Brain Dynamics

Abstract: The present article candidly states the incremental impact of nonlinear thermal radiation on heat transfer enhancement due to Darcy–Forchheimer flow of spinel-type MnFe2O4-Casson/water nanofluids due to a stretched rotating disk. In present contest, the entropy generation approach is highlighted specially as a powerful tool for the analysis of the brain function, in accordance with the theological and philosophical approach of Saint Thomas Aquinas. The some of the results of the present study that strengthening of permeability and Casson parameter contribute to the diminution of radial and tangential velocity profiles and yield shrinkage of the related boundary layers. An increase in thermal radiation leading to more heat propagating into the fluid thereby improves the TBL. Fluids with non-Newtonian behavior contribute greater entropy generation rate compared to Newtonian fluids. The most significant outcome is that the entropy generation makes a real contribution to the brain function or analysis of the function of the brain.

Ohmic Heating and Non-uniform Heat Source/Sink Roles on 3D Darcy–Forchheimer Flow of CNTs Nanofluids Over a Stretching Surface

Abstract: The major focus of the current study was the modeling of 3D Darcy–Forchheimer flow of water–CNTs nanofluid. Impacts of non-uniform heat source/sink and Ohmic heating on 3D magneto hydrodynamic flow of water–CNTs (SWCNT and MWCNT) nanofluid were assessed. The numerical analysis method ‘Runge–Kutta–Fehlberg’ was applied for existing PDEs. It was noted that the thermal boundary layer was extended for increasing Eckert numbers along $$ x\;{\text{and}}\;y $$ direction, when the fluid showed movement away from the surface. Moreover, the gap in thermal boundary layer for H2O-SWCNT was more in comparison with H2O–MWCNT nanofluid. The numerical data of this study were validated with earlier reported outcomes and were observed to have good concord.

Implementation of the One-Step One-Hybrid Block Method on the Nonlinear Equation of a Circular Sector Oscillator

Abstract: Solving nonlinear differential equation of a circular sector oscillator is of a scientific importance. Thus, to solve such equations, a single- step implicit block method involving one hybrid point with the introduction of a third derivative is proposed. To derive this method, the approximate basis solution is interpolated at {xn, xn + 3/5} while its second and third derivatives are collocated at all points {xn, xn + 3/5, xn + 1}on the integrated interval of approximation. Numerical results are presented in the form of table and graphs for the variation of different physical parameters. The study reveals that the proposed hybrid block method is zero stable, which proves that it is convergent beside a significant interval of absolute stability, thus making it suitable for solving stiff ODEs.

Heat and mass transfer analysis of MHD peristaltic flow through a complaint porous channel with variable thermal conductivity

Abstract: The MHD peristaltic motion of Bingham fluid through a uniform channel is examined under the influence of long wavelength and small Reynolds number. The impact of variable thermal conductivity, convective heat transfer, porous boundaries, and wall properties are considered. The semi-analytical technique is utilized to solve the governing nonlinear temperature equation. The effects of different parameters on the physiological quantities of interest are captured with the assistance of MATLAB programming. The assessment reveals that an ascent in a magnetic parameter reduces the velocity field. Further, an increment in the estimation of variable thermal conductivity upgrades the temperature profiles. Besides, the trapped bolus is a function of a porous parameter, and an increase in porous parameter will have the proportional increment in the other parameter.

Impact of Variable Transport Properties and Slip Effects on MHD Jeffrey Fluid Flow Through Channel

Abstract: The present paper aims at investigating the effects of variable transport properties and slip conditions on the MHD peristaltic mechanism of a Jeffrey liquid. The flow is considered to take place in an axisymmetric channel with compliant walls. The nonlinear momentum and energy equations are solved for small values of variable viscosity and thermal conductivity by utilizing the method of perturbation. Closed-form solutions are found for mass transfer equation. MATLAB programming is employed to get the pictorial representation of various parameters on axial velocity, streamlines, temperature and concentration profiles. The current investigation reveals that an increase in the value of the magnetic parameter reduces the velocity as well as temperature. Moreover, the size of the trapped bolus is seen to be a decreasing function of magnetic and Jeffery parameters.

Effect of Chemical Reaction on Bioconvective Flow in Oxytactic Microorganisms Suspended Porous Cavity

Abstract: In this paper, the bioconvective flow in a porous square cavity containing oxytactic microorganism in the presence of chemical reaction is investigated. The bioconvection flow and heat transfer in porous media are formulated based on the Darcy model of Boussinesq approximation. The governing partial differential equations are solved using the Galerkin finite element method. The computational numerical results are exhibited by the streamlines, isotherms, isoconcentrations of oxygen, isoconcentrations of microorganisms, average Nusselt number, average Sherwood numbers of oxygen concentration and microorganisms. The effects of key parameters such as bioconvection Rayleigh number (Rb), chemical reaction parameter (Kr) and thermal Rayleigh number (Ra) are presented and analyzed. It can be deduced that the chemical reaction reduces the strength of isoconcentrations of both oxygen and microorganisms. It has been revealed that the chemical reaction has a greater effect on the swimming of the microorganisms, average Nusselt number, and average density number.

Entropy-optimized radiating water/FCNTs nanofluid boundary-layer flow with convective condition

Abstract: The inherent irreversibility in boundary-layer flow of a radiating water/functionalized carbon nanotubes nanofluid over a convectively heated moving wedge and a horizontal/vertical plates is examined. The water-based nanofluid contains two types of carbon nanotubes, namely SWCNTs and MWCNTs. Using a suitable similarity transformation, the model partial differential equations are reduced to ordinary differential equations along with the corresponding boundary conditions. Solutions are obtained for the nanofluid velocity and temperature profiles analytically via optimal homotopy asymptotic method and numerically via shooting method with Runge–Kutta–Fehlberg integration scheme. Entropy generation analysis is conducted based on second law of thermodynamic, and the Bejan number is determined. Results are presented in graphical and tabular forms in order to scrutinize the effects of various geometrical, dynamical and thermophysical parameters on velocity, temperature, skin friction, Nusselt number, entropy generation rate and Bejan number. Generally, it is found that the entropy production can be minimized by reducing the convection through boundaries, moving the obstacle at the same velocity and direction as the flow (λoptimal = 1) and controlling the penetration of viscous dissipation, while increasing nanoparticles rate and thermal radiation has influence to increase the entropy generation. In addition, horizontal plate corresponding to the wedge angle value m = 0 is the optimum geometry to reduce entropy production.

Convective Heat Transfer Analysis of Hydromagnetic Micropolar Fluid Flow Past an Inclined Nonlinear Stretching Sheet with Variable Thermo-Physical Properties

Abstract: The current work examines mixed convection boundary layer flow and heat transfer attributes in hydromagnetic micropolar fluid past a heated inclined sheet which stretches nonlinearly along the direction of flow. The impact of variable thermo-physical characteristics of the fluid together with the influence of magnetic field, thermal radiation and viscous dissipation are also checked on the flow field. The modelled governing equations are translated from partial to ordinary differential equations via relevant similarity transformations and the resulting equations are subsequently solved numerically by means of shooting techniques in company with Runge-Kutta integration algorithms. The reactions of the skin friction coefficient, Nusselt number, dimensionless velocity as well as temperature to variations in the emerging controlling parameters are illustrated through different graphs. In the limiting situations, the results obtained exhibit a strong relationship with the existing related works in literature. The facts emanated from this study also reveal that the thickness of the thermal boundary layer grows widely with a rise in the Eckert number and Biot number parameters whereas increasing the material (micropolar) and thermal conductivity parameters have opposite effects on the rate of heat transfer.

Computational modelling and optimal control of measles epidemic in human population.

Abstract: Measles is an awfully contagious acute viral infection. It can be fatal, causing cough, red eyes, followed by a fever and skin rash with signs of respiratory infection. In this paper, we propose and analyze a model describing the transmission dynamics of a measles epidemic in the human population using the stability theory of differential equations. The model proposed undergoes a backward bifurcation for some parameter values. Sensitivity analysis is carried out on the model parameters in order to determine their impact on the disease dynamics. We extend the model to an optimal control problem by including time-dependent control variables: prevention, treatment of infected people and vaccination of the susceptible humans. In an attempt to minimize the infected people and the cost applied we design the cost functional. Next, we show that optimal control exists for the system, and the Pontryagin maximum principle is employed to characterize the continuous controls. Numerical simulation is performed to justify the analytical results and discussed quantitatively.

Peristaltic flow of non-Newtonian fluid through an inclined complaint nonlinear tube: application to chyme transport in the gastrointestinal tract

Abstract: Acknowledging the novel significances of a peristaltic phenomenon in various biological and physiological systems, researchers in the current decade perform admirable investigations. Studies on this topic still need attention due to the prestigious applications of the peristaltic event in the gastrointestinal tract, artificial lung, heart equipment, and blood circulation in the body. This endeavor explores the novel impact of slip on the peristaltic flow of non-Newtonian Jeffrey liquid through an inclined tube. The effect of varying fluid properties (variable viscosity and variable thermal conductivity) and wall properties is considered. The governing equations are turned dimensionless by appropriate similarity transformations. The series solution is obtained for velocity, temperature, and concentration equation. The graphical representation of pertinent parameters on the physiological flow quantities is depicted by applying MATLAB 2019b program. The obtained results reveal that the up-hosted values of the viscosity parameter enhance distributions of velocity and temperature. Further, the impact of variable viscosity slightly enhances the magnitude of the trapped bolus. Moreover, the present investigation finds its applications to examine the bright insight appliances of chyme through the gastrointestinal tract.

Optimization of thermosolutal convection in vertical porous annulus with a circular baffle

Abstract: An enclosed annular geometry with a conducting baffle attached to one of the thermally active walls aptly represents many scientific applications. This article reports the thermosolutal convection in a vertical cylindrical porous annulus with a thin baffle attached to an inner cylinder. The vertical left and right walls of the annular space are differently heated, whereas the top and bottom walls are thermally insulated. A finite difference method based numerical technique has been adapted to solve the governing model equations. Numerical simulations are carried out for various parameter ranges in the interest of capturing the influence of thermal Rayleigh, Darcy and Lewis numbers, buoyancy ratio, baffle length and location on flow pattern, heat and mass transport. From the numerical results it is found that, the heat and mass transport can be effectively enhanced or suppressed by the appropriate choices of baffle length and location. In particular, the thermal and solute transport rates are suppressed with the length of baffle. However, transport rates can be enhanced by positioning the baffle towards top adiabatic wall. Numerical predictions made in this analysis can be utilized for the design of heat exchangers and chemical impellers.

Modeling Anthrax with Optimal Control and Cost Effectiveness Analysis

Abstract: Anthrax is an infection caused by bacteria and it affects both human and animal populations. The disease can be categorized under zoonotic diseases and humans can contract infections through contact with infected animals, ingest contaminated dairy and animal products. In this paper, we developed a mathematical model for anthrax transmission dynamics in both human and animal populations with optimal control. The qualitative solution of the model behaviour was analyzed by determining Rhv, equilibrium points and sensitivity analysis. A vaccination class was incorporated into the model with waning immunity. Local and global stability of the model’s equilibria was found to be locally asymptotically stable whenever Rhv Rhv. It was revealed that reducing animal and human interaction rate, would decrease Rhv. We extended the model to optimal control in order to find the best control strategy in reducing anthrax infections. It showed that the effective strategy in combating the anthrax epidemics is vaccination of animals and prevention of humans.

Optimal Control Model and Cost Effectiveness Analysis of Maize Streak Virus Pathogen Interaction with Pest Invasion in Maize Plant

Abstract: In this paper, we proposed and analyzed an optimal control deterministic model for the dynamics of Maize Streak Virus pathogen interaction with a pest invasion on Maize plant to examine the best st...

Mathematical Modelling of Listeriosis Epidemics in Animal and Human Population with Optimal Control.

Abstract: Listeriosis is a serious disease caused by the germ Listeria monocytogenes. People usually become ill with listeriosis after eating contaminated food including meat. The disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems. In this paper, we propose and scrutinize a model problem describing the transmission dynamics of Listeriosis epidemic in animal and human population using the stability theory of differential equations. The model is qualitatively analysed for the basic reproduction number as well as possibility of forward and backward bifurcation with respect to the stability of disease free and endemic equilibria. The impact of the model parameters on the disease was evaluated via sensitivity analysis. An extension of the model to include time dependent control variables such as treatment, vaccination and education of susceptible (human) is carried out. Using Pontryagin’s Maximum Principle, we obtain the optimal control strategies needed for combating Listeriosis disease. Numerical simulation of the model is performed and pertinent results are displayed graphically and discussed quantitatively.

An Ebola model with hyper-susceptibility

Abstract: The Ebola Virus Disease is a zoonosis whose reservoir is fruit bats among other primates. Once the virus enters a human population from its supposed zoonotic reservoir, it can then spread through contact with infected persons or their body fluids. The people that are most susceptible to infection are close relatives of infected persons, healthcare givers and those dealing with deceased persons. We classify these people as being hyper-Susceptible and develop a mathematical model to study the impact of hyper-Susceptibility on the dynamics of Ebola virus disease outbreak. The model is shown to have a globally stable disease-free equilibrium point whenever the basic reproduction number R 0 is less than unity. The model is also shown to exhibit forward bifurcation, which suggests the possibility of eradication through keeping R 0 below unity. Disease spread is also shown to be highly sensitive to contact rate, transmission probability, death rate and hyper-Susceptibility. Numerical simulation of the model is also done to confirm the analytical results established.

Impact of suction/injection and heat transfer on unsteady mhd flow over a stretchable rotating disk

Abstract: In this article, the unsteady magnetohydrodynamic two-dimensional boundary layer flow and heat transfer over a stretchable rotating disk with mass suction/injection is investigated Temperature-dependent physical properties and convective boundary conditions are taken into account The governing coupled nonlinear partial differential equations are transformed into a system of ordinary differential equations by adopting the well-known similarity transformations Further, the solutions are obtained through the semi-analytical method called an Optimal Homotopy Analysis Method (OHAM) The obtained results are discussed graphically to predict the features of the involved key parameters which are monitoring the flow model The skin friction coefficient and Nusselt number are also examined The validation of the present work is verified with the earlier published results and is found to be in excellent agreement It is noticed that an increase in the viscosity parameter leads to decay in momentum boundary layer thickness, and the inverse trend is observed in the case of the temperature profile

Perturbation analysis of thermophoresis, hall current and heat source on flow dissipative aligned convective flow about an inclined plate

Abstract: This present examination researches the impacts of thermophoresis, heat source and Hall current on dissipative adjusted MHD joint convection stream about an inclined plate inserted in a permeable medium. Utilizing dimensionless variables, the system of partial differential equations is changed into dimensionless equations. By making use of perturbation technique, estimated solutions for velocity, temperature, concentration profiles, skin friction, rate of heat transfer and rate of mass transfer have been determined. The attained results are explained with an assistance of diagrams to examine the impact of distinct parameters such as Magnetic parameter (M), Aligned magnetic parameter (ξ), Schmidt number (Sc), Eckert number (Ec), inclined angle (α), Prandtl number (Pr), heat generation parameter (Q), and chemical reaction (Kr), assuming two cases viz. Case I: Gr < 0, Gm < 0 (flow on heated plate); Case II: when Gr > 0, Gm > 0(flow on cooled plate). Additionally, the impacts of the appropriate parameters on the skin-friction coefficient and rates of heat and mass transfer are numerically furnished in tabular form. Skin friction coefficients are firmly diminished as magnetic field rises. Sherwood and Nusselt numbers boost up as enhance in chemical reaction.

Influence of variable viscosity and wall properties on the peristalsis of Jeffrey fluid in a curved channel with radial magnetic field

Abstract: The current investigation attempts to address the peristalsis exhibited by a Jeffrey fluid through channels with curvature and compliant walls. The flow of fluid is exposed to an external magnetic field. Moreover, variation of the viscosity of the fluid with the spatial coordinate is considered. Long wavelength and small values of Reynolds number are considered for the mathematical modeling of the problem under scope. The system of differential equations thus obtained is non-linear, the solution for which is obtained by the method of perturbation for small values of variable viscosity. The authors have provided special emphasis on the influence of pertinent parameters on velocity and trapping phenomenon. The results obtained suggest that as the channel changes from straight to curved, the velocity profile bends away from the center of the channel. Further, the trapped bolus volume is seen to be reducing with decrease in the Hartmann number.

Cattaneo-Christov Heat Flux on an MHD 3D Free Convection Casson Fluid Flow Over a Stretching Sheet

Abstract: In this investigation, we analyze the magnetohydrodynamic (MHD) three-dimensional (3D) flow of Casson fluid over a stretching sheet using non-Darcy porous medium with heat source/sink. We also consider the Cattaneo-Christov heat flux and Joule effect. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using suitable transformations and solved by using the shooting technique. The effects of the non-dimensional governing parameters on velocity and temperature profiles are discussed with the graphs. Also, the skin friction coefficient and Nusselt number are discussed through tables. We also validate our results with the ones already available in the literature. It is found that the obtained results are in excellent agreement with the existing studies under some special cases. Our analysis reveals that the thermal relaxation parameter reduces the temperature field for the Newtonian and non-Newtonian fluid cases. It is also found that the temperature profile is decreased in the Newtonian fluid case when compared with the non-Newtonian fluid case.

Entropy Analysis of a Variable Viscosity MHD Couette Flow Between Two Concentric Pipes with Convective Cooling

Abstract: This paper addresses the combined effects of the magnetic field, thermal buoyancy force, viscous dissipation, Joule heating and temperature-dependent viscosity on the Couette flow of an incompressible conducting fluid between two concentric vertical pipes. It is assumed that convective cooling occurs at the surface of the outer moving pipe while the surface of the inner fixed pipe is maintained at a constant temperature. The nonlinear equations for momentum and energy are obtained and solved numerically using a shooting method coupled with the Runge-Kutta-Fehlberg integration procedure. Relevant results depicting the effects of embedded thermophysical parameters on the velocity and temperature profiles, skin friction, the Nusselt number, entropy generation rate and the Bejan number are presented graphically and discussed. It is found that an increase in the magnetic field intensity boosts the entropy generation rate while an increase in convective cooling lessens it.