Nor Azizah Yacob

Boundary layer flow past a stretching/shrinking surface beneath an external uniform shear flow with a convective surface boundary condition in a nanofluid

The problem of a steady boundary layer shear flow over a stretching/shrinking sheet in a nanofluid is studied numerically. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation, before being solved numerically by a Runge-Kutta-Fehlberg method with shooting technique. Two types of nanofluids, namely, Cu-water and Ag-water are used. The effects of nanoparticle volume fraction, the type of nanoparticles, the convective parameter, and the thermal conductivity on the heat transfer characteristics are discussed. It is found that the heat transfer rate at the surface increases with increasing nanoparticle volume fraction while it decreases with the convective parameter. Moreover, the heat transfer rate at the surface of Cu-water nanofluid is higher than that at the surface of Ag-water nanofluid even though the thermal conductivity of Ag is higher than that of Cu.

Mixed Convection Flow Adjacent to a Stretching Vertical Sheet in a Nanofluid

The characteristics of fluid flow and heat transfer over a stretching vertical sheet immersed in a nanofluid are investigated numerically in this paper. Three different types of nanoparticles, namely, copper Cu, alumina Al2O3, and titania TiO2, are considered, using water as the base fluid. It is found that nanofluid with titania nanoparticles has better enhancement on the heat transfer rate compared to copper and alumina nanoparticles. For a particular nanoparticle, increasing the nanoparticle fraction is to reduce the skin friction coefficient and the heat transfer rate at the surface.

Soret and Dufour Effects on Unsteady Boundary Layer Flow and HeatTransfer of Nanofluid Over a Stretching/Shrinking Sheet: A StabilityAnalysis

The effects of Soret and Dufour parameters on the boundary layer flow in nanofluid over stretching/ shrinking with time dependent is studied using Buongiorno model. The system of partial differential equations is transformed to the system of ordinary differential equations by applying similarity transformation. The results are obtained numerically using bvp4c in Matlab. The reduced skin friction coefficient reduced Nusselt number, velocity, temperature and concentration profiles are shown graphically with different values of Soret effect, Dufour effect, mass flux parameter, unsteadiness parameter, thermophoresis as well as Brownian motion parameter where the dual solutions are obtained. The unsteadiness parameter and mass flux parameter expand the range of solution for stretching/ shrinking parameter. Meanwhile, the Soret and Dufour parameters are found to affect the heat transfer rate at the surface. In order to determine the stability of the solutions, stability analysis is performed.

Hydromagnetic flow and heat transfer adjacent to a stretching vertical sheet in a micropolar fluid

An analysis is carried out for the steady 2-D mixed convection flow adjacent to a stretching vertical sheet immersed in an incompressible electrically conducting micropolar fluid. The stretching velocity and the surface temperature are assumed to vary linearly with the distance from the leading edge. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically using a finite difference scheme known as the Keller box method. The effects of magnetic and material parameters on the flow and heat transfer characteristics are discussed. It is found that the magnetic field reduces both the skin friction coefficient and the heat transfer rate at the surface for any given K and l. Conversely, both of them increase as the material parameter increases for fixed values of M and l.

Mixed convection boundary-layer flow near the stagnation-point on a vertical surface in a nanofluid

The steady boundary layer flow of a nanofluid near a stagnation point on a vertical surface is investigated. The velocity of the external flow is assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically using the Keller box method with the help of MATLAB software. The effects of the Brownian motion parameter, thermophoresis parameter, and Lewis number on the fluid flow, heat and mass transfer characteristics are analyzed and discussed. It is found that for assisting flow, the friction at the surface decreases with an increase in Lewis number while it decreases with increasing Brownian motion and thermophoresis parameters. However, the effects of Lewis number for the opposing flow showed a different trend. Moreover, increasing the Brownian motion parameter, the thermophoresis parameter and the Lewis number are to decrease the heat transfer rate at the surface...

Unsteady boundary layer flow of nanofluid over a moving surface with partial slip

This study discussed on the unsteady boundary layer over a moving surface with partial slip in nanofluid using Buongiorno’s model. The system of partial differential equations is transformed to ordinary differential equations using similarity transformation and has been solved by bvp4c in Matlab to obtain the numerical solutions. The numerical solutions are obtained for skin friction coefficient, local Nusselt number as well as local Sherwood number for various moving parameter for different slip parameter. The velocity, temperature and nanoparticle volume fraction profiles are presented in order to support the findings. The results revealed that increasing slip parameter increases the shear stress, heat and mass transfer at the surface.This study discussed on the unsteady boundary layer over a moving surface with partial slip in nanofluid using Buongiorno’s model. The system of partial differential equations is transformed to ordinary differential equations using similarity transformation and has been solved by bvp4c in Matlab to obtain the numerical solutions. The numerical solutions are obtained for skin friction coefficient, local Nusselt number as well as local Sherwood number for various moving parameter for different slip parameter. The velocity, temperature and nanoparticle volume fraction profiles are presented in order to support the findings. The results revealed that increasing slip parameter increases the shear stress, heat and mass transfer at the surface.

Numerical Solutions of Forced Convection Boundary Layer Flow Towards a Horizontal Permeable Stretching Sheet in ZnO–Water, ZnO–Kerosene, MgO–Water and MgO–Kerosene Nanofluids

Nanofluid is a fluid where the nanoparticles with size less than 100 nm are dispersed in the base fluid to produce a fluid with high thermal conductivity rather than conventional fluid. Previous studies show that different nanoparticles and base fluid give different effects on the flow and heat transfer characteristics of nanofluids. The aim of the study is to numerically investigate these two characteristics on a forced convection boundary layer flow towards a horizontal permeable stretching sheet in four types of nanofluids which are ZnO–water, ZnO–Kerosene, MgO–water and MgO–Kerosene. The partial differential equations of the present problem are reduced to the boundary layer equations using boundary layer approximation. The resulting equations are then reduced to the ordinary differential equations by applying similarity transformation which is then solved numerically using a Keller box method. It is found that the skin friction coefficient and heat transfer rate at the surface for MgO–water and MgO–Kerosene nanofluids are greater than ZnO–water and ZnO–Kerosene.

Unsteady boundary layer rotating flow and heat transfer in a copper-water nanofluid over a shrinking sheet

The study of unsteady three-dimensional boundary layer rotating flow with heat transfer in Copper-water nanofluid over a shrinking sheet is discussed. The governing equations in terms of partial differential equations are transformed to ordinary differential equations by introducing the appropriate similarity variables which are then solved numerically by a shooting method with Maple software. The numerical results of velocity gradient in x and y directions, skin friction coefficient and local Nusselt number as well as dual velocity and temperature profiles are shown graphically. The study revealed that dual solutions exist in certain range of s > 0.

Boundary layer flow near a stagnation point on a permeable vertical surface immersed in a nanofluid

A steady mixed convection boundary layer flow near a stagnation point on a permeable vertical surface immersed in a nanofluid is investigated. The velocity of the external flow is assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically using the Keller box method with the help of MATLAB software. The effects of physical parameters such as the suction/injection parameter, Brownian motion parameter, thermophoresis parameter and Lewis number on the heat and mass transfer rate at the surface as well as the temperature and concentration profiles are analyzed and discussed. Both assisting and opposing flows are considered. It is found that, increasing the thermophoresis parameter, Brownian motion parameter and Lewis number are to decrease the heat transfer rate at the surface, but on the other hand increase the mass transfer rate at the surface for both assisting...

Stagnation-point flow over a nonlinearly stretching/shrinking sheet in a micropolar fluid

The problem of a steady stagnation-point flow towards a nonlinearly stretching/shrinking sheet immersed in an incompressible micropolar fluid is studied. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations using a similarity transformation, before being solved numerically by a shooting method. The results show that increasing the material parameter K is to increase the skin friction coefficient (in absolute sense). Moreover, dual solutions are found to exist for the shrinking sheet, whereas the solution is unique for the stretching case.