Rohana Abdul Hamid

Non-alignment stagnation-point flow of a nanofluid past a permeable stretching/shrinking sheet: Buongiorno’s model

The paper deals with a stagnation-point boundary layer flow towards a permeable stretching/shrinking sheet in a nanofluid where the flow and the sheet are not aligned. We used the Buongiorno model that is based on the Brownian diffusion and thermophoresis to describe the nanofluid in this problem. The main purpose of the present paper is to examine whether the non-alignment function has the effect on the problem considered when the fluid suction and injection are imposed. It is interesting to note that the non-alignment function can ruin the symmetry of the flows and prominent in the shrinking sheet. The fluid suction will reduce the impact of the non-alignment function of the stagnation flow and the stretching/shrinking sheet but at the same time increasing the velocity profiles and the shear stress at the surface. Furthermore, the effects of the pertinent parameters such as the Brownian motion, thermophoresis, Lewis number and the suction/injection on the flow and heat transfer characteristics are also taken into consideration. The numerical results are shown in the tables and the figures. It is worth mentioning that dual solutions are found to exist for the shrinking sheet.

The Non-Alignment Stagnation-Point Flow Towards a Permeable Stretching/Shrinking Sheet in a Nanofluid Using Buongiorno’s Model: A Revised Model

Abstract A numerical study on the stagnation-point boundary layer flow of a viscous and incompressible (Newtonian) fluid past a stretching/shrinking sheet with the fluid suction using Buongiorno’s model is considered. The main focus of this article is the effects of the non-alignment of the flow and the surface of the sheet. We have also studied the problem using a new boundary condition that is more physically realistic which assumes that the nanoparticle fraction at the surface is passively controlled. The governing equations of this problem are reduced to the ordinary differential equations using some similarity transformations which are then solved using the bvp4c function in Matlab. From the results obtained, we concluded that the effect of the non-alignment function is the same as in the regular fluid or nanofluid. However, it is found that the fluid suction can reduce the effect of the non-alignment at the surface. Dual solutions have also been discovered in this problem and from the stability analysis it is found that the first solution is stable while the second solution is not stable.

Thermal Diffusion and Diffusion Thermo Effects on MHD Thermosolutal Marangoni Convection Boundary Layer Flow over a Permeable Surface

The problem of thermal diffusion and diffusion thermo effects on thermosolutal Marangoni convection flow of an electrically conducting fluid over a permeable surface is investigated. Using appropriate similarity transformations, the governing system of partial differential equation is transformed to a set of nonlinear ordinary differential equations, then solved numerically using the Runge-Kutta-Fehlberg method. The effects of thermal diffusion and diffusion thermo, magnetic field parameter, thermosolutal surface tension ratio, and suction/injection parameter on the flow field, heat transfer characteristic, and concentration are thoroughly examined. Numerical results are obtained for temperature and concentration profiles as well as the local Nusselt and Sherwood numbers are presented graphically and analyzed. It is found that these governing parameters affect the variations of the temperature and concentration and also the local Nusselt and Sherwood numbers.

Boundary layer flow of a dusty fluid over a permeable shrinking surface

Purpose n n n n nThe purpose of this paper is to numerically study the boundary layer problem for the case of two-dimensional flow of dusty fluid over a shrinking surface in the presence of the fluid suction at the surface. n n n n nDesign/methodology/approach n n n n nThe governing equations of the problem are reduced to the system of ordinary differential equations using the similarity transformation and then solved using the bvp4c method in the Matlab software. n n n n nFindings n n n n nThe effects of the drag coefficient parameter L, the fluid–particle interaction parameter δ, the suction parameter s and the particle loading parameter ω on the flow of the permeable shrinking sheet are investigated. It is found that the aforementioned parameters have different effects in the shrinking sheet flow. This study has also succeeded in discovering the second solution, and through the stability analysis, it is suggested that the solution is unstable and not physically realizable in practice. n n n n nPractical implications n n n n nThe current findings add to a growing body of literature on the boundary layer problem in the dusty fluid. The dusty fluid is significant in various practical applications such as in the transporting suspended powdered materials through pipes, propulsion and combustion in rockets, the flow of blood in arteries, wastewater treatment and as corrosive particles in engine oil flow. n n n n nOriginality/value n n n n nEven though the dusty fluid problem has been extensively studied in the flow of the stretching sheet, limited findings can be found over a shrinking flow. In fact, this is the first study to discover the second solution in the dusty fluid problem.

MHD boundary layer flow of a Maxwell nanofluid over a permeable vertical surface

The MHD boundary layer flow of a Maxwell nanofluid over a permeable vertical surface is studied. The governing nonlinear partial differential equations are transformed into ordinary differential equations using similarity transformation and solved numerically using a shooting method. The effects of suction/injection on the velocity, temperature and concentration profiles as well as the heat transfer characteristics are discussed and graphically presented. It is found that the suction parameter increase the velocity profiles, while the opposite behavior for the injection parameter.

MHD boundary layer flow and heat transfer due to an exponentially shrinking sheet in a nanofluid with thermal radiation and chemical reaction

In this paper, the problem of magnetohydrodynamic (MHD) boundary layer flow and heat transfer of a nanofluid with the influences of the chemical reaction and thermal radiation over an exponentially shrinking sheet is studied numerically. The model used for the nanofluid is called the Buongiorno model which incorporates the effects of the Brownian motion and thermophoresis. The governing dimensionless ordinary differential equations are solved using the bvp4c method. The effects of the magnetic field parameter, thermal radiation parameter and chemical reaction parameter on the velocity, temperature and concentration profiles of the nanofluid over an exponentially permeable shrinking sheet are discussed and presented through graphs and tables.

The effects of chemical reaction and thermal radiation on MHD boundary layer flow of a nanofluid over an exponentially stretching/shrinking sheet: A revised model

In the present study, the effects of chemically reactive species and thermal radiation on magnetohydrodynamic (MHD) boundary layer flow and heat transfer in a nanofluid over an exponentially stretching/shrinking sheet are numerically investigated. We have used a revised Buongiorno’s nanofluid model, which is more realistic physically that assumed the nanoparticle fraction at the boundary is passively controlled. The governing partial differential equations are reduced to the ordinary differential equations using an appropriate similarity transformation and then solved numerically using the bvp4c function in the Matlab software. The effects of the governing parameters of interest are analyzed and discussed in detail and presented in the form of figures and tables. It is found that the second solution exist in the exponentially shrinking flow.

Stagnation point flow, heat transfer and species transfer over a shrinking sheet with coupled Stefan blowing effects from species transfer

The problem of stagnation-point flow and heat transfer with the effect of the blowing from species transfer over an impermeable shrinking sheet is studied. The governing boundary layer equations are transformed into the ordinary differential equations using the similarity transformations which are then solved numerically using the bvp4c function in Matlab. The focus of this study is the effect of the blowing parameter to the velocity of the flow, the rate of heat transfer and the mass of species transfer over a flat surface of shrinking sheet. From the numerical results, it is found that the blowing parameter substantially affects the flow, heat and mass transfer characteristics.

Stability analysis of MHD thermosolutal Marangoni convection boundary layer flow

In this paper, the steady magnetohydrodynamic (MHD) Marangoni convection boundary layer flow over a flat surface is investigated. The governing equations are transformed into ordinary differential equations using some similarity transformations which are then solved numerically using the bvp4c function in Matlab. From the numerical results obtained, dual solutions are found to exist within a certain range of the thermosolutal surface tension ratio. A stability analysis is performed to determine the physically realizable solution and it is found that the first solution is stable while the second solution is not stable.

Marangoni mixed convection boundary layer flow with suction and injection

The mixed Marangoni convection boundary layer flow over a permeable surface in the presence of thermal-diffusion and diffusion-thermo effects is investigated. The governing partial differential equations are converted into a set of nonlinear ordinary differential equations using similarity transformations and then solved numerically using the Runge-Kutta-Fehlberg method. The effects of the governing parameters namely buoyancy or mixed convection parameter, suction/injection parameter, Dufour and Soret numbers on the velocity, temperature and concentration fields are presented graphically and analyzed. It is found that the surface velocity increases with the increasing of the mixed convection parameter.