Browsing by Author "Mutuku, W. N."

Now showing 1 - 5 of 5
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    An optimal Control Model for Coffee Berry Disease and Coffee Leaf Rust Co-infection
    (Journal of Mathematical Analysis and Modeling, 2024) Nyaberi, H. O.; Mutuku, W. N.; Malonza, D. M.; Gachigua, G. W.; Alworah, G. O.
    In the 1980s, coffee production in Kenya peaked at an average of 1.7 million bags annually. Since then, this production has declined to the current output of below 0.9 million bags annually. Coffee berry disease (CBD) and Coffee leaf rust (CLR) are some of the causes of this decline. This is due to insufficient knowledge of optimal control strategies for CBD and CLR co-infection. In this research, we derive a system of ODEs from the mathematical model for co-infection of CBD and CLR with control strategies to perform optimal control analysis. An optimal control problem is formulated and solved using Pontryagin’s maximum principle. The outcomes of the model’s numerical simulations indicate that combining all interventions is the best strategy for slowing the spread of the CBD-CLR co-infection.
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    Analysis of Ethylene Glycol (EG)-based ((Cu-Al2O3), (Cu-TiO2), (TiO2-Al2O3)) Hybrid Nanofluids for Optimal Car Radiator Coolant
    (Journal of Engineering Research and Reports, 2020) Okello, John A.; Mutuku, W. N.; Oyem, A. O.
    Coolants are vital in any automotive since they manage the heat in the internal combustion of the engines by preventing corrosion in the cooling system as well as assist in eradicating the engine’s waste heat. This paper examines three different types of ethylene glycol-based hybrid nanofluids ((Cu-Al2O3), (Cu-TiO2), (TiO2-Al2O3)) to establish their cooling capabilities for industrial cooling applications. The vertical flow of these hybrid nanofluids combination through a semi-infinite convectively heated flat plate mimicking the flow of coolant in car radiator is modeled. The governing non-linear partial differential equations of fluid flow are transformed into a system of coupled non-linear ordinary differential equations using a suitable similarity transformation variables and the numerical solution executed using the shooting technique together with the fourth-order Runge-Kutta-Fehlberg integration scheme. The numerical simulation is executed using MATLAB and results are displayed graphically. The effects of pertinent parameters on velocity, temperature, skin friction, and local Nusselt number are investigated. From the study (Cu-Al2O3 hybrid nanocoolant leads to a rapid decrease in temperature at the boundary layer.
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    Buoyancy-Induced MHD Stagnation Point Flow of Williamson Fluid with Thermal Radiation
    (Journal of Engineering Research and Reports., 2020) Ouru, J. O.; Mutuku, W. N.; Oke, A. S.
    Flow of fluids subjected to thermal radiation has enormous application in polymer processing, glass blowing, cooling of nuclear reactant and harvesting solar energy. This paper considers the MHD stagnation point flow of non-Newtonian pseudoplastic Williamson fluid induced by buoyancy in the presence of thermal radiation. A system of nonlinear partial differential equations suitable to describe the MHD stagnation point flow of Williamson fluid over a stretching sheet is formulated and then transformed using similarity variables to boundary value ordinary differential equations. The graphs depicting the effect of thermal radiation parameter, buoyancy and electromagnetic force on the fluid velocity and temperature of the stagnation point flow are given and the results revealed that increase in buoyancy leads to an increase in the overall velocity of the flow but a decrease in the temperature of the flow.
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    Hydromagnetic thermal boundary layer of nanofluids over a convectively heated flat plate with viscous dissipation and ohmic heating
    (2014) Mutuku, W. N.; Oluwole, Daniel Makinde
    This paper examines the effect of the complex interaction between the electrical conductivity of the conventional base fluid and that of the nanoparticles under the influence of magnetic field in a boundary layer flow with heat transfer over a convectively heated flat surface. Three types of water based nanofluids containing metallic or non-metallic nanoparticles such as copper (Cu), Alumina (Al2O3) and Titania (TiO2) are investigated. Using a similarity analysis of the model transport equations followed by their numerical computations, the results for the nanofluids velocity, temperature, skin friction and Nusselt number are obtained. The effects of various thermophysical parameters on the boundary layer flow characteristics are displayed graphically and discussed quantitatively. It is observed that the presence of nanoparticles greatly enhance the magnetic susceptibility of nanofluids as compared to the convectional base fluid
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    LHAM Approach to Fractional Order Rosenau-Hyman and Burgers' Equations
    (Asian Research Journal of Mathematics, 2020) Ajibola, S. O.; Oke, A. S.; Mutuku, W. N.
    Fractional calculus has been found to be a great asset in nding fractional dimension in chaos theory, in viscoelasticity di usion, in random optimal search etc. Various techniques have been proposed to solve di erential equations of fractional order. In this paper, the Laplace-Homotopy Analysis Method (LHAM) is applied to obtain approximate analytic solutions of the nonlinear Rosenau-Hyman Korteweg-de Vries (KdV), K(2, 2), and Burgers' equations of fractional order with initial conditions. The solutions of these equations are calculated in the form of convergent series. The solutions obtained converge to the exact solution when α = 1, showing the reliability of LHAM.