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- Item3D simulation of incompressible Poiseuille flow through 180° curved duct of square cross-section under effect of thermal buoyancy(Budapest University of Technology and Economics, 2019-08-04) Mokeddem, Mourad; Laidoudi, Houssem; Makinde, Oluwole Daniel; Bouzit, Mohamed
Show more In this paper, three-dimensional numerical simulations are carried out to investigate and analyze the gradual effects of thermal buoyancy strength on laminar flow of an incompressible viscous fluid and heat transfer rate inside a 180° curved channel of square cross-section. The governing equations of continuity, momentum and energy balance are obtained and solved numerically using finite volume method. The effect of Dean number, De, and Richardson number, Ri, on dimensionless velocity profiles and Nusselt number are examined for the conditions: De = 125 to 150, Ri = 0 to 2 at Pr = 1. The mean results are illustrated in terms of streamline and isotherm contours to interpret the flow behaviors and its effect on heat transfer rate. Dimensionless velocity profiles and the local Nusselt number at the angle 0° and 90° are presented and discussed. Also, the average Nusselt number on surfaces of curved duct is computed. The obtained results showed that by adding thermal buoyancy to computed domain, some early Dean vortices are observed at the angle 0° and new sort are observed at 90°. Furthermore, increase in Dean number increases the heat transfer rate. In other hand, increase in Richardson number decreases the average Nusselt number of 180° curved duct.Show more - ItemChemically reacting on MHD boundary-layer flow of nanofluids over a non-linear stretching sheet with heat source/sink and thermal radiation(Thermal Science, 2018) Makinde, Oluwole Daniel; Mabood, Fazle; Ibrahim, Mohammed S.
Show more In this paper, steady 2-D MHD free convective boundary-layer flows of an electrically conducting nanofluid over a non-linear stretching sheet taking into account the chemical reaction and heat source/sink are investigated. The governing equations are transformed into a system of non-linear ODE using suitable similarity transformations. Analytical solution for the dimensionless velocity, temperature, concentration, skin friction coefficient, heat and mass transfer rates are obtained by using homotopy analysis method. The obtained results show that the flow field is substantially influenced by the presence of chemical reaction, radiation, and magnetic field.Show more - ItemEffects of thermal radiation on MHD peristaltic motion of walters-B fluid with heat source and slip conditions(Regional Information Center for Science and Technology, 2017) Makinde, O. D.; Reddy, M. Gnaneswara; Reddy, K. Venugopal
Show more In this paper, we examine the combined effects of magnetic field, thermal radiation, heat source, velocity slip and thermal jump on peristaltic transport of an electrically conducting Walters-B fluid through a compliant walled channel. Using small wave number approach, the nonlinear model differential equations are obtained and tackled analytically by regular perturbation method. Expressions for the stream function, velocity, temperature, skin-friction coefficient and heat transfer coefficient are constructed. Pertinent results are presented graphically and discussed quantitatively. It is found that the velocity distribution depresses while the fluid temperature rises with an increase in Hartmann number. The trapping phenomenon is observed and the size of trapped bolus increases with an increase in Hartmann number.Show more - ItemHeat and mass transfer analysis of MHD peristaltic flow through a complaint porous channel with variable thermal conductivity(IOP Science, 2020-02-18) Vaidya, H.; Rajashekhar, C.; Manjunatha, G.; Prasad, K. V.; Makinde, O. D.; Vajravelu, K.
Show more 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.Show more - ItemThe impact of saccharomyces cerevisiae on a wine yeast consortium in natural and inoculated fermentations(Frontiers Media, 2017) Bagheri, Bahareh; Bauer, Florian; Setati, Mathabatha E.
Show more Natural, also referred to as spontaneous wine fermentations, are carried out by the native microbiota of the grape juice, without inoculation of selected, industrially produced yeast or bacterial strains. Such fermentations are commonly initiated by non-Saccharomyces yeast species that numerically dominate the must. Community composition and numerical dominance of species vary significantly between individual musts, but Saccharomyces cerevisiae will in most cases dominate the late stages of the fermentation and complete the process. Nevertheless, non-Saccharomyces species contribute significantly, positively or negatively, to the character and quality of the final product. The contribution is species and strain dependent and will depend on each species or strain’s absolute and relative contribution to total metabolically active biomass, and will therefore, be a function of its relative fitness within the microbial ecosystem. However, the population dynamics of multispecies fermentations are not well understood. Consequently, the oenological potential of the microbiome in any given grape must, can currently not be evaluated or predicted. To better characterize the rules that govern the complex wine microbial ecosystem, a model yeast consortium comprising eight species commonly encountered in South African grape musts and an ARISA based method to monitor their dynamics were developed and validated. The dynamics of these species were evaluated in synthetic must in the presence or absence of S. cerevisiae using direct viable counts and ARISA. The data show that S. cerevisiae specifically suppresses certain species while appearing to favor the persistence of other species. Growth dynamics in Chenin blanc grape must fermentation was monitored only through viable counts. The interactions observed in the synthetic must, were upheld in the natural must fermentations, suggesting the broad applicability of the observed ecosystem dynamics. Importantly, the presence of indigenous yeast populations did not appear to affect the broad interaction patterns between the consortium species. The data show that the wine ecosystem is characterized by both mutually supportive and inhibitory species. The current study presents a first step in the development of a model to predict the oenological potential of any given wine mycobiome.Show more - ItemImpact of second order slip and non-uniform suction on non-linear stagnation point flow of alumina-water nanofluid over electromagnetic sheet(International Information and Engineering Technology Association, 2019) Nayak, Manoj Kumar; Zeeshan, Ahmad; Pervaiz, Zeshan; Makinde, Oluwole Daniel
Show more The purpose of the present article is to study the influence of second order slip and variable suction on non-linear stagnation point flow of Alumina-water nanofluid past an electromagnetic sheet embedded in a porous medium. A simulation model was established through hybrid Homotopy Analysis Method (HAM) and Genetic Algorithm Method (GAM). Through this it was found that favorable pressure gradient and modified Hartmann number yield accelerated fluid motion while porous matrix and first order slip result in decelerated flow over stationary/moving electromagnetic sheet. The finding of this research may serve as greater cooling agent due to more heat transfer rate from the electromagnetic sheet subject to favorable pressure gradient.Show more - ItemImpact of thermophoretic transport of Al₂O₃ nanoparticles on viscoelastic flow of oil-based nanofluid over a porous exponentially stretching surface with activation energy(Institute of Fundamental Technological Research, 2019) Etwire, Christian John; Seini, Ibrahim Yakubu; Rabiu, Musah; Makinde, Oluwole Daniel
Show more The influence of thermophoretic transport of Al₂O₃ nanoparticles on heat and mass trans- fer in viscoelastic flow of oil-based nanofluid past porous exponentially stretching surface with activation energy has been examined. Similarity technique was employed to transform the gov- erning partial differential equations into a coupled fourth-order ordinary differential equations which were reduced to a system of first-order ordinary differential equations and then solved numerically using the fourth-order Runge-Kutta algorithm with a shooting method. The re- sults for various controlling parameters were tabulated and graphically illustrated. It was found that the thermophoretic transport of Al₂O₃ nanoparticles did not affect the rate of flow and heat transfer at the surface but it affected the rate of mass transfer of the nanofluid which decayed the solutal boundary layer thickness. This study also revealed that activation energy retards the rate of mass transfer which causes a thickening of the solutal boundary layer.Show more - ItemIrreversibility analysis of hydromagnetic flow of couple stress fluid with radiative heat in a channel filled with a porous medium(Elsevier, 2017) Eegunjobi, A. S.; Makinde, O. D.
Show more Numerical analysis of the intrinsic irreversibility of a mixed convection hydromagnetic flow of an electrically conducting couple stress fluid through upright channel filled with a saturated porous medium and radiative heat transfer was carried out. The thermodynamics first and second laws were employed to examine the problem. We obtained the dimensionless nonlinear differential equations and solves numerically with shooting procedure joined with a fourth order Runge-Kutta-Fehlberg integration scheme. The temperature and velocity obtained, used to analyse the entropy generation rate together with some various physical parameters of the flow. Our results are presented graphically and talk over.Show more - ItemA mathematical model for coinfection of listeriosis and anthrax diseases(Hindawi, 2018) Osman, Shaibu; Makinde, Oluwole Daniel
Show more Listeriosis and Anthrax are fatal zoonotic diseases caused by Listeria monocytogene and Bacillus Anthracis, respectively. In this paper, we proposed and analysed a compartmental Listeriosis-Anthrax coinfection model describing the transmission dynamics of Listeriosis and Anthrax epidemic in human population using the stability theory of differential equations. Our model revealed that the disease-free equilibrium of the Anthrax model only is locally stable when the basic reproduction number is less than one. Sensitivity analysis was carried out on the model parameters in order to determine their impact on the disease dynamics. Numerical simulation of the coinfection model was carried out and the results are displayed graphically and discussed. We simulate the Listeriosis-Anthrax coinfection model by varying the human contact rate to see its effects on infected Anthrax population, infected Listeriosis population, and Listeriosis-Anthrax coinfected population.Show more - ItemMHD slip flow and heat transfer over an exponentially stretching permeable sheet embedded in a porous medium with heat source(Global Digital Central, 2017) Sharma, P. R.; Choudhary, Sushila; Makinde, O. D.
Show more Steady two dimensional laminar magnetohydrodynamic (MHD) slip flow and heat transfer of a viscous incompressible and electrically conducting fluid past over a flat exponentially non-conducting stretching porous sheet embedded in a porous medium with non uniform permeability in the presence of non uniform heat source is investigated. The governing equations of velocity and temperature distributions are solved numerically and the effects of different physical parameters are shown through graphs. The rate of shear stress and the rate of heat transfer at the sheet are derived, discussed numerically and their numerical values for various values of physical parameters are presented through tables.Show more - ItemMHD slip flow of Casson fluid along a nonlinear permeable stretching cylinder saturated in a porous medium with chemical reaction, viscous dissipation, and heat generation/absorption(MDPI, 2019) Ullah, Imran; Alkanhal, Tawfeeq Abdullah; Shafie, Sharidan; Nisar, Kottakkaran Sooppy; Khan, Ilyas; Makinde, Oluwole Daniel
Show more The aim of the present analysis is to provide local similarity solutions of Casson fluid over a non-isothermal cylinder subject to suction/blowing. The cylinder is placed inside a porous medium and stretched in a nonlinear way. Further, the impact of chemical reaction, viscous dissipation, and heat generation/absorption on flow fields is also investigated. Similarity transformations are employed to convert the nonlinear governing equations to nonlinear ordinary differential equations, and then solved via the Keller box method. Findings demonstrate that the magnitude of the friction factor and mass transfer rate are suppressed with increment in Casson parameter, whereas heat transfer rate is found to be intensified. Increase in the curvature parameter enhanced the flow field distributions. The magnitude of wall shear stress is noticed to be higher with an increase in porosity and suction/blowing parameters.Show more - ItemMHD variable viscosity mixed convection of nanofluid in a microchannel with permeable walls(CSIR-NIScPR, 2020) Kefene, Mesfin Zewde; Makinde, Oluwole Daniel; Enyadene, Lemi Guta
Show more In this study, we examine the combined effects of buoyancy forces, pressure gradient, thermophoresis, Brownian motion, variable viscosity of nanofluid flow in a microchannel with suction and injection in the presence of uniform magnetic field imposed in cross-wise direction. It is assumed that the dynamic viscosity of the nanofluid is related with temperature exponentially and that the vertical parallel-plates temperature is held asymmetrically. Applying similarity transformation, the governing system of partial differential equations (PDEs) are transformed into a set of non-dimensional nonlinear partial differential equations whose solutions are obtained numerically by semi-discretization centered finite difference method along with Runge-Kutta Fehlberg integration technique scheme. Qualitative description of graphical results depicting the effect of thermophysical parameters on the dimensionless velocity, temperature, nanoparticles concentration, skin friction, Nusselt number and Sherwood number are presented.Show more - ItemModelling and optimal control of pneumonia disease with cost-effective strategies(Informa UK Limited, trading as Taylor & Francis Group, 2017) Tilahun, Getachew Teshome; Makinde, Oluwole Daniel; Malonza, David
Show more We propose and analyse a nonlinear mathematical model for the transmission dynamics of pneumonia disease in a population of varying size. The deterministic compartmental model is studied using stability theory of differential equations. The effective reproduction number is obtained and also the asymptotic stability conditions for the disease free and as well as for the endemic equilibria are established. The possibility of bifurcation of the model and the sensitivity indices of the basic reproduction number to the key parameters are determined. Using Pontryagin's maximum principle, the optimal control problem is formulated with three control strategies: namely disease prevention through education, treatment and screening. The cost-effectiveness analysis of the adopted control strategies revealed that the combination of prevention and treatment is the most cost-effective intervention strategies to combat the pneumonia pandemic. Numerical simulation is performed and pertinent results are displayed graphically.Show more - ItemModelling and optimal control of typhoid fever disease with cost-effective strategies(Hindawi Publishing Corporation, 2017-09) Tilahun, Getachew Teshome; Makinde, Oluwole Daniel; Malonza, David
Show more We propose and analyze a compartmental nonlinear deterministic mathematical model for the typhoid fever outbreak and optimal control strategies in a community with varying population.The model is studied qualitatively using stability theory of differential equations and the basic reproductive number that represents the epidemic indicator is obtained from the largest eigenvalue of the next-generation matrix. Both local and global asymptotic stability conditions for disease-free and endemic equilibria are determined. The model exhibits a forward transcritical bifurcation and the sensitivity analysis is performed.The optimal control problem is designed by applying Pontryagin maximum principle with three control strategies, namely, the prevention strategy through sanitation, proper hygiene, and vaccination; the treatment strategy through application of appropriate medicine; and the screening of the carriers. The cost functional accounts for the cost involved in prevention, screening, and treatment together with the total number of the infected persons averted. Numerical results for the typhoid outbreak dynamics and its optimal control revealed that a combination of prevention and treatment is the best cost-effective strategy to eradicate the disease.Show more - ItemOptimal control and cost effectiveness analysis for Newcastle disease eco-epidemiological model in Tanzania(Informa UK Limited, trading as Taylor & Francis Group, 2017) Hugo, Alfred; Makinde, Oluwole Daniel; Kumar, Santosh; Chibwana, Fred F.
Show more In this paper, a deterministic compartmental eco- epidemiological model with optimal control of Newcastle disease (ND) in Tanzania is proposed and analysed. Necessary conditions of optimal control problem were rigorously analysed using Pontryagin’s maximum principle and the numerical values of model parameters were estimated using maximum likelihood estimator. Three control strategies were incorporated such as chicken vaccination (preventive), human education campaign and treatment of infected human (curative) and its’ impact were graphically observed. The incremental cost effectiveness analysis technique used to determine the most cost effectiveness strategy and we observe that combination of chicken vaccination and human education campaign strategy is the best strategy to implement in limited resources. Therefore,NDcan be controlled if the farmers will apply chicken vaccination properly and well in time.Show more - ItemParameter estimation and sensitivity analysis of Dysentery diarrhea epidemic model(Hindawi, 2019) Berhe, Hailay Weldegiorgis; Makinde, Oluwole Daniel; Theuri, David Mwangi
Show more In this paper, dysentery diarrhea deterministic compartmental model is proposed. The local and global stability of the disease- free equilibrium is obtained using the stability theory of differential equations. Numerical simulation of the system shows that the backward bifurcation of the endemic equilibrium exists for 𝑅₀ > 1. The system is formulated asa standard nonlinear least squares problem to estimate the parameters. The estimated reproduction number, based on the dysentery diarrhea disease data for Ethiopia in 2017, is 𝑅₀ = 1.1208. This suggests that elimination of the dysentery disease from Ethiopia is not practical. A graphical method is used to validate the model. Sensitivity analysis is carried out to determine the importance of model parameters in the disease dynamics. It is found out that the reproduction number is the most sensitive to the effective transmission rate of dysentery diarrhea (𝛽). It is also demonstrated that control of the effective transmission rate is essential to stop the spreading of the disease.Show more - ItemSoret and Dufour effects on MHD flow with heat and mass transfer past a permeable stretching sheet in presence of thermal radiation(NISCAIR-CSIR, 2017) Sreedevi, G.; Rao, D. R. V. Prasada; Makinde, O. D.; Reddy, G. Venkata Ramana
Show more An analysis has been carried out to study the combined effects of the magnetic field, Joule heating, thermal radiation absorption, viscous dissipation, Buoyancy forces, thermal-diffusion and diffusion-thermion the convective heat and mass transfer flow of an electrically conducting fluid over a permeable vertically stretching sheet. The boundary layer equations for the fluid flow, heat and mass flux under consideration have been obtained and reduced into a system of non-linear ordinary differential equations by using appropriate similarity transformation. Using shooting method coupled with the fourth order Runge-Kutta integration scheme, the numerically solutions have been obtained and presented graphically. The effects of various embedded thermo-physical parameters on the fluid velocity, temperature, skin friction, Nusselt number and Sherwood number have been determined and discussed quantitatively. A comparison of a special case of our results with the one previously reported in the literature shows a very good agreement. An increase in values of thermal radiation, viscous dissipation, suction/injection coefficient and chemical reaction results in the increase of velocity, temperature and heat-mass transfer rates. It is further noted that the velocity, temperature and heat-mass transfer rates reduces on the boundary layer of a permeable vertical stretching sheet due to increase in the values of Soret or decrease in values of Dufour. Further, this work leads to study different flows of electrically conducting fluid over a permeable vertical stretching sheet problem that includes the two dimensional non-linear boundary equations.Show more - ItemThermal decomposition analysis in a sphere of combustible materials(Sage, 2017) Lebelo, Ramoshweu Solomon; Makinde, Oluwole Daniel; Chinyoka, T.
Show more In this article, we look at spontaneous combustion due to exothermic chemical reaction taking place within a stockpile of combustible material. The model includes mass and energy balance equations in a spherical domain. The complicated chemical reaction is simplified by considering a one-dimensional process. The differential equations governing the problem are solved using semi-implicit finite difference method. The effects of kinetic parameters embedded within the system are analyzed and the results are expressed graphically and discussed accordingly.Show more - ItemThermophoresis and Brownian Motion Effects on Magnetohydrodynamics Electro-Osmotic Jeffrey Nanofluid Peristaltic Flow in Asymmetric Rotating Microchannel(American Scientific Publishers, 2019-03) Reddy, K. Venugopal; Reddy, M. Gnaneswara; Makinde, O. D.
Show more This article investigates with the thermophoresis and Brownian motion effects on MHD electro-osmotic Jeffrey nanofluid peristaltic flow in an asymmetric microchannel. Well established large wavelength and small Reynolds number approximations are invoked. Numerical solutions have been evaluated for the stream function, nanofluid velocity, nanofluid temperature and nanoparticle phenomena. The computed results for nanofluid velocity, temperature, and concentration fields are utilized to determine the skin-friction, Nusselt number, and Sherwood number. The graphical results have been presented and discussed for various involved parameters. The novel features of nanofluids made them potentially significant in heat and mass transfer mechanism occurring in medical and industrial processes like microelectronics, pharmaceutical processes, hybrid engines, thermal management of vehicles, refrigerator, chiller, gas temperature reduction and so forth. These processes bear tendency to enhance thermal conductivity and the convective heat transfer more efficiently than base fluid. This unique aspect made nanofluids the topic of interest in recent time via different fluid flow models. The problem at hand is one such application of nanofluids in peristaltic flow through the asymmetric rotating microchannel.Show more