Power Law Variation In Surface Temperature Research Articles

Micropolar fluid flow and heat transfer about a spinning cone with Hall current and Ohmic heating

In this paper, the laminar boundary layer flow of an electrically conducting micropolar fluid about a spinning cone with Hall current, Ohmic heating, and power-law variation in surface temperature is studied analytically. The governing equations are transformed into a dimensionless system of four nonlinear coupled partial differential equations. These equations have been solved analytically subject to the relevant boundary conditions by employing homotopy analysis method. The convergence of the obtained series solutions is carefully checked. Graphical results are presented to investigate the influence of the magnetic parameter, the Hall parameter, and the Eckert number on the axial velocity, the tangential velocity, the microrotation, and the temperature. For near the cone surface, the magnitude of microrotation velocity increases for free convection regime and decreases for forced convection regime as magnetic parameter increases, but the behavior is completely reversed as one moves away from the cone surface. Besides, in the immediate vicinity of the cone, the effect of increasing the Hall parameter is to increase very slightly the magnitude of microrotation velocity for free convection regime, while the magnitude of microrotation velocity decreases for forced convection regime as the Hall parameter increases, but the converse is apparent as one moves toward the edge of the boundary layer.

Influence of surface mass transfer on mixed convection flows over non-isothermal horizontal flat plates

Non-similar solution of a steady mixed convection flow over a horizontal flat plate in the presence of surface mass transfer (suction or injection) is obtained when there is power-law variation in surface temperature. The surface temperature is assumed to vary as a power of the axial coordinate measured from the leading edge of the plate. A non-similar mixed convection parameter is considered which covers the whole convection regime, namely from pure free convection to pure forced convection. Numerical results are reported here to account the effects of Prandtl number, surface temperature, surface mass transfer parameter (suction or injection) on velocity and temperature profiles, and skin friction and heat transfer coefficients.

Natural convection of a micropolar fluid from a vertical truncated cone with power-law variation in surface temperature

This work presents a boundary-layer analysis about the natural convection heat transfer near a vertical truncated cone with power-law variation in surface temperature in a micropolar fluid. The transformed boundary layer governing equations are solved by the cubic spline collocation method. Results for local Nusselt numbers are presented as functions of vortex viscosity parameter, the surface temperature exponent, and the Prandtl number. The heat transfer rates of the truncated cones with higher surface temperature exponents are higher than those with lower surface temperature exponents. Moreover, the heat transfer rate from a vertical truncated cone in Newtonian fluids is higher than that in micropolar fluids.

Viscous dissipation and Joule heating effects on MHD-free convection from a vertical plate with power-law variation in surface temperature in the presence of Hall and ion-slip currents

An analysis is presented to study the effects of viscous dissipation and Joule heating on MHD-free convection flow past a semi-infinite vertical flat plate in the presence of the combined effect of Hall and ion-slip currents for the case of power-law variation of the wall temperature. The fluid is permeated by a strong transverse magnetic field imposed perpendicularly to the plate on the assumption of a small magnetic Reynolds number. The governing differential equations are transformed by introducing proper non-similarity variables and solved numerically. The effects of various parameters on the velocity and temperature profiles as well as the local wall shear stresses and the local Nusselt number are presented graphically and in tabular form. It is found that the magnetic field acts as a retarding force on the tangential flow but has a propelling effect on the induced lateral flow. The skin-friction factor for the tangential flow and the local Nusselt number decrease but the skin-friction factor for the lateral flow increases as the magnetic field increases. The skin-friction factor for the tangential and lateral flows are increased while the local Nusselt number is decreased if the effect of viscous dissipation, Joule heating and heat generation are considered. The opposite trend was observed as the temperature power coefficient n is increased. Also, the skin-friction factor for the tangential flow and the local Nusselt number are increased due to the Hall and ion-slip currents, whereas the skin-friction factor for the tangential flow increases when Hall values increase to one and decreases for values of Hall greater than one, but reduces by rising ion-slip values.

Laminar mixed convection over horizontal flat plates with power-law variation in surface temperature

An analysis is performed to study the heat transfer characteristics of laminar mixed convective boundary-layer flow over a semi-infinite horizontal flat plate with non-uniform surface temperatures. The surface temperature is assumed to vary as a power of the axial coordinate measured from the leading edge of the plate. A nonsimilar mixed convection parameter χ and a pseudo-similarity variable η are introduced to cast the governing boundary layer equations and their boundary conditions into a system of dimensionless equations which are solved numerically by a weighted finite-difference method. The mixed convection parameter χ is chosen so that χ = 0 corresponds to pure free convection and χ = 1 corresponds to pure forced convection. Numerical results are presented for Prandtl numbers of 0.1, 0.7, 7 and 100 and representative values of the exponent n for the power-law variation in wall temperature. The heat transfer results are compared with existing correlations for the uniform wall temperature case and new correlations are derived for the general case of power-law wall temperature variations. It is found that an increase in the Prandtl number and exponent value n increases the local heat transfer rate.