MHD power-law fluid flow and heat transfer over a non-isothermal stretching sheet

This article presents a numerical solution for the magnetohydrodynamic (MHD) non-Newtonian power-law fluid flow over a semi-infinite non-isothermal stretching sheet with internal heat generation/absorption. The flow is caused by linear stretching of a sheet from an impermeable wall. Thermal conductivity is assumed to vary linearly with temperature. The governing partial differential equations of momentum and energy are converted into ordinary differential equations by using a classical similarity transformation along with appropriate boundary conditions. The intricate coupled non-linear boundary value problem has been solved by Keller box method. It is important to note that the momentum and thermal boundary layer thickness decrease with increase in the power-law index in presence/absence of variable thermal conductivity

A study of flow and heat transfer of nanofluids: between two parallel plates, over a wedge and past a stretching sheet

This thesis investigates analytically and numerically the flow and heat transfer of nanofluids: between two infinite parallel plates, over a wedge, and past a stretching sheet. Two problems have been considered for the parallel plates. A mathematical model of squeezing unsteady nanofluid flow is studied firstly in the presence of thermal radiation, and secondly, in the presence of both thermal radiation and heat generation/absorption. The solutions are obtained by using homotopy perturbation method (HPM) and fourth-order Runge-Kutta with shooting technique (RK4). The flow of nanofluids over a wedge leads to the derivation of the Falkner-Skan equation and this problem have been solved using the optimal homotopy asymptotic method (OHAM). Finally, three issues have been considered for nanofluids past the stretching sheet. Firstly, we considered a problem of flow and heat transfer of nanofluids over a dynamic stretching sheet with non-linear velocity and variable thickness in the presence of Brownian motion and thermal radiation. Secondly, the effect of a chemical reaction is taken into account. These two problems have been investigated using the OHAM and RK4. Lastly, a mathematical model for the effect of chemical reaction in a natural convective boundary-layer flow of nanofluids has been evolved. The HPM with Pade approximation (HPM-Pade) along with RK4 is used to solve the nonlinear governing equations. It is found that the thermal radiation had recorded a significant influence, in which it has been observed that the growing value of the thermal radiation parameter results to the decrease in the temperature profile in the case of squeezing flow problem. Thereby both the thermal boundary layer thickness and temperature profile have substantially risen in the flow and heat transfer over a stretching sheet cases. From the subsequent cases, we also found that the temperature is high due to the increase in both the Brownian motion and the thermophoresis parameters, while the scenario reverses as the nanoparticle concentration only increases with the strengthen thermophoresis parameter and slow down with an increase in the Brownian motion parameter

Thermal stratification effects on MHD radiative flow of nanofluid over nonlinear stretching sheet with variable thickness

The combined effects of thermal stratification, applied electric and magnetic fields, thermal radiation, viscous dissipation and Joules heating are numerically studied on a boundary layer flow of electrical conducting nanofluid over a nonlinearly stretching sheet with variable thickness. The governing equations which are partial differential equations are converted to a couple of ordinary differential equations with suitable similarity transformation techniques and are solved using implicit finite difference scheme. The electrical conducting nanofluid particle fraction on the boundary is passively rather than actively controlled. The effects of the emerging parameters on the electrical conducting nanofluid velocity, temperature, and nanoparticles concentration volume fraction with skin friction, heat transfer characteristics are examined with the aids of graphs and tabular form. It is observed that the variable thickness enhances the fluid velocity, temperature, and nanoparticle concentration volume fraction. The heat and mass transfer rate at the surface increases with thermal stratification resulting to a reduction in the fluid temperature. Electric field enhances the nanofluid velocity which resolved the sticking effects caused by a magnetic field which suppressed the profiles. Radiative heat transfer and viscous dissipation are sensitive to an increase in the fluid temperature and thicker thermal boundary layer thickness. Comparison with published results is examined and presented

Heat Transfer in Boundary Layer Viscolastic Fluid Flow Over Anexponentially Stretching Sheet

The paper presents the study of momentum and heat transfer characteristics in a visco-elastic boundary layer fluid flow over an exponentially stretching continuous sheet with non-uniform heat source. The flow is generated solely by the application of two equal and opposite forces along the x-axis such that stretching of the boundary surface is of exponential order in x and influenced by uniform magnetic field applied vertically. The non-linear boundary layer equation for momentum is converted into ordinary differential equation by means of similarity transformation. Approximate analytical similarity solutions is obtained for the dimensionless stream function and velocity distribution function after transforming the boundary layer equation into Riccati type and solving it sequentially. Heat transfer equation is then solved using Runge-Kutta fourth order method. The accuracy of the analytical solutions is also verified by comparing the solutions obtained to those in literature when Hartmann number is zero. The effects of various physical parameters on velocity, skin friction, temperature and Nusselt number profiles are presented graphically

Magneto-bioconvection flow of a Casson thin film with nanoparticles over an unsteady stretching sheet : HAM and GDQ computation

Purpose – To numerically investigate the two-dimensional unsteady laminar magnetohydrodynamic (MHD) bioconvection flow and heat transfer of an electrically-conducting non-Newtonian Casson thin film with uniform thickness over a horizontal elastic sheet emerging from a slit in the presence of viscous dissipation. The composite effects of variable heat, mass, nanoparticle volume fraction and gyrotactic micro-organism flux are considered as is hydrodynamic (wall) slip. The Buongiorno nanoscale model is deployed which features Brownian motion and thermophoretic effects. The model studies the manufacturing fluid dynamics of smart magnetic bio-nano-polymer coatings. Design/Methodology/Approach – The coupled non-linear partial differential boundary-layer equations governing the flow, heat and nano-particle and micro-organism mass transfer are reduced to a set of coupled non-dimensional equations using the appropriate transformations and then solved as an nonlinear boundary value problem with the semi-numerical Liao homotopy analysis method (HAM).Validation with a generalized differential quadrature (GDQ) numerical technique is included. Findings – An increase in velocity slip results in a significant decrement in skin friction coefficient and Sherwood number whereas it generates a substantial enhancement in Nusselt number and motile micro-organism number density. The computations reveal that the bioconvection Schmidt number decreases the micro-organism concentration and boundary-layer thickness which is attributable to a rise in viscous diffusion rate. Increasing bioconvection Péclet number substantially elevates the temperatures in the regime, thermal boundary layer thickness, nanoparticle concentration values and nano-particle species boundary layer thickness. The computations demonstrate the excellent versatility of HAM and GDQ in solving nonlinear multi-physical nanobioconvection flows in thermal sciences and furthermore are relevant to application in the synthesis of smart biopolymers, microbial fuel cell coatings etc. Originality/Value – The originality of the study is to address the simultaneous effects of unsteady and variable surface fluxes on Casson nanofluid transport of gyrotactic bio-convection thin film over a stretching sheet in the presence of a transverse magnetic field. Validation of HAM with a generalized differential quadrature (GDQ) numerical technique is included. Keywords – Magneto-hydrodynamics, Bioconvection, Nanofluid, Brownian motion, Homotopy analysis method (HAM), Generalized differential quadrature (GDQ

The effects of lawsonia inermis pigmentation for superhydrophobic properties on cotton fabrics

Nowadays, there are many things that can be produced easily by the help of modern technologies. This include the synthetic materials that can be developed by using any advance machine that was manufactured [1]. However, those synthetics materials that was developed may bring harm to the environment. Their particles can be spread resulting an unhealthy atmosphere. Thus, the natural resources was used to produce an authentic materials (Calarge, 2018). In the recent years, textile industry has been developed significantly and contributes to the growth of Malaysia’s economy [2]. It can be categorized as one of the complicated industries among the manufacturing industries such as food, cosmetics and pharmaceutical industries [3]. Thus, the textile industries require high water consumption and resulting on high discharge rate of wastewater that loaded with contaminants [2]. The generation of wastewater from textile industry comes from the manufacturing process of textile fabrics such as washing scouring bleaching, mercerizing, and dyeing and finishing process. The highest amount of wastewater that produced from textile industries come from the process of dyeing and finishing. The contaminants of water that produced by dyeing and finishing process include high suspended solids (SS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), heat, colour, acidity, basicity, and other organic pollutants [4]. This matter has to be seriously concerned as it may lead to allergic responses, eczema, and also affect the liver, lungs, and immune system of humans as well as animals [3]. The purpose for the project of the effects of Lawsonia Inermis was basically to produce a natural pigment that may not harm the environmen

Combined effects of internal heat generation and buoyancy force on boundary layer over a vertical plate with a convective surface boundary condition

This paper considers the effect of buoyancy force and internal heat generation on laminar thermal boundary layer over a vertical plate with a convective surface boundary condition. We assumed that left surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the right surface with a heat source that decays exponentially. Using a similarity variable, the steady state governing non-linear partial differential equations have been transformed into a set of coupled non-linear ordinary differential equations, which are solved numerically by applying shooting iteration technique together with fourth order Runge-Kutta integration scheme. The effects of Prandtl number, local Biot number, the internal heat generation parameter and the local Grashof number on the velocity and temperature profiles are illustrated and interpreted in physical terms. A comparison with previously published results on special case of the problem shows excellent agreemen