Abstract
In this study, the steady laminar mixed convection boundary layer flow of a nanofluid near the stagnation-point on a vertical plate with prescribed surface temperature is investigated. Here, both assisting and opposing flows are considered and studied. Using appropriate transformations, the system of partial differential equations is transformed into an ordinary differential system of two equations, which is solved numerically by shooting method, coupled with Runge-Kutta scheme. Three different types of nanoparticles, namely copper Cu, alumina Al R 2 R O R 3 R and titania TiO R 2 R with water as the base fluid are considered. Numerical results are obtained for the skin-friction coefficient and Nusselt number as well as for the velocity and temperature profiles for some values of the governing parameters, namely, the nanoparticle volume fraction parameter ���� and mixed convection parameter λ It is found that the highest rate of heat transfer occurs in the mixed convection with assisting flow while the lowest one occurs in the mixed convection with opposing flow. Moreover, the skin friction coefficient and the heat transfer rate at the surface are highest for copper-water nanofluid compared to the alumina-water and titania-water nanofluids.
Highlights
Nanofluids are a new class of nanotechnologybased heat transfer fluids engineered by dispersing nanometer-scale solid particles with typical length scales on the order of 1 to 100 nm in traditional heat transfer fluids (Das et al, 2007)
The majority of treatments of this problem are limited to cases in which the flow is directed vertically upward, while the situation when the flow is directed downward. It appears that separation in mixed convection flow was first discussed by Merkin (1969), who examined the effect of opposing buoyancy forces on the boundary layer flow on a semi-infinite vertical flat plate at uniform temperature in a uniform free stream
Motivated by the above investigations, the present paper studies when the mixed convection boundary layer flow is introduced normal to the vertical plate
Summary
Nanofluids are a new class of nanotechnologybased heat transfer fluids engineered by dispersing nanometer-scale solid particles with typical length scales on the order of 1 to 100 nm in traditional heat transfer fluids (Das et al, 2007). The majority of treatments of this problem are limited to cases in which the flow is directed vertically upward (assisting flow), while the situation when the flow is directed downward (opposing flow) It appears that separation in mixed convection flow was first discussed by Merkin (1969), who examined the effect of opposing buoyancy forces on the boundary layer flow on a semi-infinite vertical flat plate at uniform temperature in a uniform free stream. This problem was studied further by Wilks (1973) and Hunt and Wilks (1980), who considered the case of uniform flow over a semi-infinite flat plate heated at a constant heat flux rate. We discuss on the effect of solid volume fraction of nanoparticles as well as their types on the fluid flow and heat transfer characteristics and show that nanofluid enhances the thermal conductivity, which is generally low for a regular fluid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
