Mixed Convection Boundary Layer Flow over a Vertical Flat Plate with Radiative Heat Transfer

In this article, the problem of mixed convection boundary layer flow of viscous fluid along a heated vertical plate is examined. In the analysis radiative component of heat flux emulates the surface temperature. Appropriate set of variables are embraced here which reduces the governing boundary layer equations into dimensionless form. Subsequently, a group of continuous transformation is applied on the dimensionless equations in order to obtain the parabolic partial differential equations for the regimes where modified Richardson number, Ri*, is 1) small i.e. when Ri* 1, 2) large i.e. when Ri* 1, and 3) covers all its values i.e. when 0 ≤ Ri* ≤ ∞. The system of equation for the corresponding regimes are thus integrated numerically via straightforward finite difference method along with Gaussian elimination technique. Its worth mentioning that results obtained here are valid particularly for the liquid metals for which Pr 1. Moreover, the numerical results are demonstrated graphically by showing the effects of important physical parameters, namely, the modified Richardson number (or mixed convection parameter), Ri*, surface radiation parameter, R, and Prandtl number, Pr, in terms of local skin friction and local Nusselt number coefficients. In addition, comprehensive interpretation of thermal energy distributions is also given in terms of heatlines which is termed as good tool to visualize the flow patterns.

A Study on Heat Transfer Enhancement through Various Nanofluids in a Square Cavity with Localized Heating

A two-dimensional(2D)laminar flow of nanofluids confined within a square cavity having localized heat source at the bottom wall has been investigated.The governing Navier–Stokes and energy equations have been non dimensionalized using the appropriate non dimensional variables and then numerically solved using finite volume method.The flow was controlled by a range of parameters such as Rayleigh number,length of heat source and nanoparticle volume fraction.The numerical results are represented in terms of isotherms,streamlines,velocity and temperature distribution as well as the local and average rate of heat transfer.A comparative study has been conducted for two different base fluids,ethylene glycol and water as well as for two different solids Cu and Al_(2)O_(3).It is found that the ethylene glycol-based nanofluid is superior to the water-based nanofluid for heat transfer enhancement.

Transient Combined Convective Heat Transfer over a Stretching Surface in a Non-Newtonian Nanofluid Using Buongiorno’s Model

The present paper investigates the transient mixed convective boundary layer flow of an incompressible non-Newtonian quiescent nanofluid adjacent to a vertical stretching surface. The effects of the Brownian motion and thermophoresis are included for the nanofluid. Using appropriate non-similarity transformations the non-dimensional, coupled and highly non-linear system of equations is solved numerically using the efficient Keller-box implicit finite difference method for the whole transient from t=0 (initial state) to (final steady-state flow). The box method is unconditionally stable. Numerical results for dimensionless velocity (f’), micro-rotation (g), temperature (θ), nanoparticle volume fraction (Φ) at final steady state flow, skin friction function (), Nusselt number function () and Sherwood number function () have been presented on various parameters inform of tables and graphs. The results indicate that as Nb and Nt increase, the Nusselt number decreases whereas Sherwood number increases at initial and early state time but decreases at the final steady state time. As the K increases, the friction factor decreases whereas surface mass transfer rate and the surface heat transfer rates slightly increase. The results reveal that there is a smooth transition of flow from unsteady state to the final steady state. A special case of our results is in good agreement with an earlier published work. The study has many practical applications such as extrusion of plastic sheets, paper production, glass blowing, metal spinning and drawing plastic films.