Purpose
The purpose of this paper is to perform a numerical study for heat transfer through natural convection in the presence of a constant magnetic field in an incompressible steady nanofluid flow inside an isosceles triangular cavity.
Design/methodology/approach
For this flow problem, the left wall of the cavity subjected to uniform/nonuniform heat was considered, while right and bottom walls of the cavity were kept cold. The obtained equations were solved by using the Galerkin weighted residual technique. Results are computed for a wide range of parameters including Rayleigh number (Ra) (10^3 < Ra < 10^7), Hartman number (Ha) (0 < Ha < 60), and heat-generation/-absorption coefficient (q) (−10 < q < 10), while, Prandtl number (Pr) was kept fixed at 6.2. These computed results are presented in terms of stream functions, isotherms, Nusselt numbers and average Nusselt numbers through figures.
Findings
It is observed that, in case of uniform heating of the side wall, the strength of stream lines’ circulations increases with an increase in Ra and decreases with an increase in Ha. Similarly, by increasing heat-absorption coefficient q, an increase in the circulation strength is noted and the circulation cell moves towards the left wall in the presence of a heat sink (q < 0) and moves to the cold right wall in the presence of a heat source (q > 0). In the case of nonuniformly heated left wall in the presence of a heat source (q > 0), a higher-temperature gradient is observed in the cavity and isotherms are clustered to the left wall in the lower portion and to right wall in the upper portion; these appear to be straight and parallel to the x-axis near the bottom wall. On the other hand, the heat transfer rate along all the walls of the cavity is observed to be higher for smaller values of q. Whereas, Nusselt number along the bottom wall (Nu-B) increases with an increase in the values of x, while, that along the left wall (Nu-L) first increases and then decreases. But Nusselt number along the right wall (Nu-R) is found to be qualitatively opposite to Nu-L with an increase in distance x. Whereas, average Nusselt number increases with an increase in Rayleigh number Ra and heat-generation/-absorption coefficient q.
Research limitations/implications
The problem is formulated for an incompressible flow; viscous dissipation has been neglected, negligible induced magnetic field has been considered and local thermal equilibrium has been considered.
Originality/value
Results presented in this paper are original and new for the effects of a uniform magnetic field on the natural convection of Cu–water nanofluid in a triangular cavity. Hence, this study is important for researchers working in the area of heat transfer in cavity flows involving the nanofluid to become familiar with the flow behavior and properties.
Polymer modification of commercially available bitumen has been attempted by the incorporation of liquid natural rubber (LNR) of medium viscosity. Both soft and blown bitumens have been studied. Physical and rheological characteristics of the samples were investigated. Improvement in physical properties such as shear strength and ductility in the case of blown bitumen and resistance to flow in the case of soft bitumen were observed. It was also found that as a result of addition of LNR, the activation energy of flow increases in the case of soft bitumen and decreases in blown bitumen.
In this article, numerical simulations are carried out for fluid flow and heat transfer through natural convection in an isosceles triangular cavity under the effects of uniform magnetic field. The cavity is of cold bottom wall and uniformly/non-uniformly heated side walls and is filled with isotropic porous medium. The governing Navier Stoke's equations are subjected to Penalty finite element method to eliminate pressure term and Galerkin weighted residual method is applied to obtain the solution of the reduced equations for different ranges of the physical parameters. The results are verified as grid independent and comparison is made as a limiting case with the results available in literature, and it is shown that the developed code is highly accurate. Computations are presented in terms of streamlines, isotherms, local Nusselt number and average Nusselt number through graphs and tables. It is observed that, for the case of uniform heating side walls, strength of circulation of streamlines gets increased when Rayleigh number is increased above critical value, but increase in Hartmann number decreases strength of streamlines circulations. For non-uniform heating case, it is noticed that heat transfer rate is maximum at corners of bottom wall.
Solutions for the equations of motion of an incompressible third grade fluid are obtained by employing transformation methods. First, the hodograph transformation is applied to the equations to interchange the independent and dependent variables. Then a Legendre‐transform function is introduced and all equations are written in terms of this function and the conditions this function should satisfy are determined. Several illustrations of the method are considered and the results with the linear viscous fluid case are compared. It is noted that the results in the third grade fluid are considerably different from the corresponding results of the viscous fluid.
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