Anati Ali

Unsteady Mixed Convection Boundary Layer from a Circular Cylinder in a Micropolar Fluid

Most industrial fluids such as polymers, liquid crystals, and colloids contain suspensions of rigid particles that undergo rotation. However, the classical Navier-Stokes theory normally associated with Newtonian fluids is inadequate to describe such fluids as it does not take into account the effects of these microstructures. In this paper, the unsteady mixed convection boundary layer flow of a micropolar fluid past an isothermal horizontal circular cylinder is numerically studied, where the unsteadiness is due to an impulsive motion of the free stream. Both the assisting (heated cylinder) and opposing cases (cooled cylinder) are considered. Thus, both small and large time solutions as well as the occurrence of flow separation, followed by the flow reversal are studied. The flow along the entire surface of a cylinder is solved numerically using the Keller-box scheme. The obtained results are compared with the ones from the open literature, and it is shown that the agreement is very good.

The unsteady boundary layer flow past a circular cylinder in micropolar fluids

Purpose – The purpose of this paper is to study the unsteady boundary layer flow of a micropolar fluid past a circular cylinder which is started impulsively from rest.Design/methodology/approach – The nonlinear partial differential equations consisting of three independent variables are solved numerically using the 3D Keller‐box method.Findings – Numerical solutions for the velocity profiles, wall skin friction and microrotation profiles are obtained and presented for various values of time t and material parameter K with the boundary condition for microrotation n=0 (strong concentration of microelements) and n=1/2 (weak concentration of microelements). The results are presented along the points on the cylinder surface, starting from the forward to the rear stagnation point, for small time up to the time when the boundary layer flow separates from the cylinder.Originality/value – It is believed that this is the first paper that uses the 3D Keller‐box method to study the unsteady boundary layer flow of mic...

Mixed convection flow of viscoelastic fluid over a sphere under convective boundary condition embedded in porous medium

The investigation on mixed convection boundary layer of a viscoelastic fluid over a sphere which is embedded in porous medium under convective boundary condition is carried out in this paper. The boundary layer equations of viscoelastic fluid are an order higher than Newtonian (viscous) fluid and the adherence boundary conditions are insufficient to determine the solution of these equations completely. Hence, the augmentation on extra boundary conditions is needed in order to solve this problem. The governing partial differential equations are first transformed into non-dimensional forms and then solved numerically using the Keller-box method by augmenting extra boundary conditions at infinity. The numerical results obtained for limiting case are comparing with related outcomes in order to validate the present results. Results on the effects of the viscoelastic parameter in the presence of porosity and mixed convection on the skin friction and heat transfer as well as velocity and temperature profile have been discussed.

The effects of heat generation or absorption on MHD stagnation point of Jeffrey fluid

The analysis on the problem of heat generation/absorption effects on MHD stagnation point of Jeffrey Fluid is carried out. The governing partial differential equations are first transform as first order ordinary differential equation using similarity transformation before solving using numerical scheme called Keller-box. A comparative study with the previous results is made in order to verify the validation of the present results. The results for the skin friction and heat transfer coefficient as well as velocity and temperature profiles are presented and discussed in details for various values of heat generation/absorption parameter, magnetic parameter, Deborah number and Prandtl number.

Unsteady Mixed Convection Boundary Layer Flow past a Sphere in a Micropolar Fluid

The unsteady mixed convection flow over a sphere in a micropolar fluid is studied. The unsteadiness is due to an impulsive motion of the free stream. The governing boundary layer equations are first reduced into a non-dimensional form. The nondimensional equations are transformed into a set of non-similarity boundary layer equations. The solutions are obtained numerically using an efficient implicit finite-difference method known as the Keller-Box method. The algorithm for 3D Keller-Box method has been developed. The numerical results obtained are presented through tables and graphs. The results show that the parameters such as material, microrotation and mixed convection parameters for assisting and opposing cases have strong influence on the fluid motion.

Influence of aligned MHD on convective boundary layer flow of viscoelastic fluid

Effects of aligned Magnetohydrodynamics (MHD) on the mixed convection boundary layer flow of viscoelastic fluid past a circular cylinder with Newtonian heating is investigated. Appropriate transformation is applied to the governing partial differential equations to transform them into dimensionless forms which are then solved using finite difference method known as Keller box. For verification purpose, the preliminary numerical solutions of the model are compared with previous study with a particular condition that the magnetic and viscosity effect are both absent. With strong agreement between the previous and current results, the authors believe that the extended outcome produced from the present model is accurate. Findings from the study will be presented in tabular and graphical form.

Mixed convective boundary layer flow of a dusty Jeffrey fluid over an exponentially stretching sheet

A numerical model was developed to study the effect of magnetic field on a boundary layer flow and convective heat transfer of a dusty Jeffrey fluid over an exponentially stretching surface for a steady case. The similarity transformation are used to reduce the system of governing partial differential equations into set of non-linear ordinary differential equations. The reduced similarity equations are then solved numerically by using Runge-Kutta-Fehlberg fourth-fifth method (RKF45) with the help of Maple. The influence of physical parameters such as the magnetic parameter, Prandtl number, Deborah number, mixed convection parameter, the local fluid-particle interaction parameter and heat transfer characteristics are analyzed and discussed in details through tables and graph. Thereafter the obtained numerical results are found to be in good agreement when compared with result for a Newtonian fluid.

Magnetohydrodynamic flow of dusty fluid past a vertical stretching sheet with Hall effect

The investigation on hydromagnetic flow of dusty fluid with Hall effect over a vertical surface of stretching sheet has been conducted. The governing partial differential equations are transformed into ordinary differential equations by using similarity transformation. The resulting differential equations are solved numerically by using Runge Kutta Fehlberg forth-fifth method (RKF45 Method). The effects of magnetic parameter, fluid-particle interaction parameter, Grashof number and Hall parameter on velocity and temperature profiles are presented graphically. The numerical values of the velocity gradient and wall temperature gradient are also shown in a tabular form.

Unsteady hydromagnetic flow of dusty fluid and heat transfer over a vertical stretching sheet with thermal radiation

In this paper, the hydromagnetic flow of dusty fluid over a vertical stretching sheet with thermal radiation is investigated. The governing partial differential equations are reduced to nonlinear ordinary differential equations using similarity transformation. These nonlinear ordinary differential equations are solved numerically using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The behavior of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid is analyzed and discussed for different parameters of interest such as unsteady parameter, fluid-particle interaction parameter, the magnetic parameter, radiation parameter and Prandtl number on the flow.

Hydromagnetic mixed convection flow over an exponentially stretching sheet with fluid-particle suspension

The present paper deals with the study of a convective heat transfer characteristics of an incompressible viscous dusty fluid over an exponentially stretching surface with an exponential temperature distribution. The similarity transformation is used to reduce the system of governing partial differential equations into a set of non-linear ordinary differential equations which is then solved numerically using Runge-Kutta-Fehlberg fourth-fifth method (RKF45) with the help of Maple. The influence of physical parameters such as the Prandtl number, mixed convection parameter, the local fluid-particle interaction parameter, Eckert number and the magnetic parameter on the flow and heat transfer characteristics are analyzed and discussed in details through tables and graphs. The behavior of velocity and temperature profile of hydromagnetic mixed convection flow with fluid-particle suspension are assumed to have specific exponential function forms. The present numerical results are compared with the earlier published results.