F. M. Hady

Radiation effect on viscous flow of a nanofluid and heat transfer over a nonlinearly stretching sheet

In this work, we study the flow and heat transfer characteristics of a viscous nanofluid over a nonlinearly stretching sheet in the presence of thermal radiation, included in the energy equation, and variable wall temperature. A similarity transformation was used to transform the governing partial differential equations to a system of nonlinear ordinary differential equations. An efficient numerical shooting technique with a fourth-order Runge-Kutta scheme was used to obtain the solution of the boundary value problem. The variations of dimensionless surface temperature, as well as flow and heat-transfer characteristics with the governing dimensionless parameters of the problem, which include the nanoparticle volume fraction ϕ, the nonlinearly stretching sheet parameter n, the thermal radiation parameter NR, and the viscous dissipation parameter Ec, were graphed and tabulated. Excellent validation of the present numerical results has been achieved with the earlier nonlinearly stretching sheet problem of Cortell for local Nusselt number without taking the effect of nanoparticles.

Mixed convection-radiation interaction in boundary-layer flow over horizontal surfaces

The effect of buoyancy forces and thermal radiation on the steady laminar plane flow over an isothermal horizontal flat plate is investigated within the framework of first-order boundary-layer theory, taking into account the hydrostatic pressure variation normal to the plate. The fluid considered is a gray, absorbing-emitting but nonscattering medium, and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. Both a hot surface facing upward and a cold surface facing downward are considered in the analysis. Numerical results for the local Nusselt number, the local wall shear stress, the local surface heat flux, as well as the velocity and temperature distributions are presented for gases with a Prandtl number of 0.7 for various values of the radiation-conduction parameter, the buoyancy parameter, and the temperature ratio parameter.

Mixed convection boundary-layer flow of non-Newtonian fluids on a horizontal plate

Abstract The transfer processes of steady laminar mixed convection of non-Newtonian fluids along a horizontal plate for uniform wall temperature is investigated. The effects of the index of the power-law viscosity model, buoyancy parameter, and generalized Prandtl number on the local heat transfer and skin friction coefficients are investigated for selected values of ξ.

Heat transfer from a continuous surface in a parallel free stream of viscoelastic fluid

SummaryThe effect of uniform suction or injection on flow and heat transfer from a continuous surface in a parallel free stream of viscoelastic second-order fluid is investigated. A perturbation method is used to obtain solutions for the transformed governing equations. The velocity profiles, temperature profiles, skin friction parameters and heat transfer parameters are computed for various values of the suction/injection parameter, λ.

Effect of a transverse magnetic field and porosity on the Falkner-Skan flows of a non-Newtonian fluid

This paper provides an analysis of the effects of a uniform transverse magnetic field and porosity on the boundary layer flow of a homogeneous incompressible of the second grad past a wedge placed symmetrically with respect to the flow direction. The variation of the skin friction with respect to porosity and magnetic field parameters are discussed. Also the first order velocities of the fluid are given graphically.

Mixed convection over a horizontal plate with vectored mass transfer in a transverse magnetic field

An exact similarity solution is presented for developing mixed convection flows of electrically conducting fluids over a semi-infinite horizontal plate with vectored mass transfer at the wall which are subjected to an applied transverse magnetic field. This solution is given for the case of a wall temperature that is inversely proportional to the square root of the distance from the leading edge. By application of appropriate coordinate transformations, the governing momentum and energy boundary-layer equations are expressed as a set of coupled ordinary differential equations that depend on a magnetic parameter, the buoyancy parameter, and the Prandtl number. The shear stress, the total heat transfer, and the displacement thickness are calculated for different values of both buoyancy and magnetic parameters.

Soret effect on natural convection boundary-layer flow of a non- Newtonian nanofluid over a vertical cone embedded in a porous medium

In this investigation, we intend to present the influence of the prominent Soret effect on natural convection boundary-layer flow of a non-Newtonian nanofluid over a vertical cone embedded in a porous medium. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The governing partial differential equations are transformed into a set of non-linear equations and solved numerically using an efficient numerical shooting technique with a fourth-order Runge-Kutta scheme (MATLAB package). The numerical results for the temperature, volume fraction, and concentration profiles, as well as the

Boundary-Layer Flow in a Porous Medium of a Nanofluid Past a Vertical Cone

The natural convection flow over a surface embedded in saturated porous media is encountered in many engineering problems such as the design of pebble-bed nuclear reactors, ceramic processing, crude oil drilling, geothermal energy conversion, use of fibrous material in the thermal insulation of buildings, catalytic reactors and compact heat exchangers, heat transfer from storage of agricultural products which generate heat as a result of metabolism, petroleum reservoirs, storage of nuclear wastes, etc.

Natural Convection of a Nanofluid in Inclined, Partially Open Cavities: Thermal Effects

This paper discusses the phenomenon of natural convection flow in an inclined, partially open enclosure filled with Al2O3–water nanofluid. In the cavity, the horizontal walls and the closed portions of the right wall are thermally insulated. Three thermal cases were considered for the left wall; in the first case, the left wall was considered to be uniformly heated; in the second case, a heat source was attached to the left wall; and in the third, the left wall had a heat sink. For case 2, there is a heat source attached to the left wall. For case 3, the left wall contains a heat sink. The partial differential equations governing the problem were solved numerically using the finite difference method. The obtained results were presented by the local Nusselt number, the average Nusselt number, streamlines, and isotherms with various pertinent parameters, namely, the Rayleigh number (103≤Ra≤106), the solid volume fraction (0≤ϕ≤0.2), different lengths of the heat source/sink (0.2≤BL≤1), different locations of...

Convection flow over a uniform-flux vertical surface with variable viscosity

A regular perturbation analysis is presented for natural convection flow over an uniform flux vertical surface with temperature dependent viscosity. Numerical calculations are presented forPr=6.7 which show that the first-order correction to the local temperature difference and to the local skin-fraction are negative whereas it is positive for the local Nusselt number. The effects of variable viscosity on the temperature, velocity profiles, the local temperature difference, the local Nusselt number and the local skin fraction are discussed.