scholarly journals Dual solutions of stagnation-point flow of a nanofluid over a stretching surface

2013 ◽  
Vol 2013 (1) ◽  
pp. 188 ◽  
Author(s):  
Peri K Kameswaran ◽  
Precious Sibanda ◽  
Chetteti RamReddy ◽  
Prabhala VSN Murthy
Meccanica ◽  
2012 ◽  
Vol 47 (7) ◽  
pp. 1623-1632 ◽  
Author(s):  
Tapas Ray Mahapatra ◽  
Samir Kumar Nandy ◽  
Kuppalapalle Vajravelu ◽  
Robert A. Van Gorder

Engineering ◽  
2010 ◽  
Vol 02 (04) ◽  
pp. 299-305 ◽  
Author(s):  
Tapas R. Mahapatra ◽  
Samir K. Nandy ◽  
Anadi S. Gupta

Author(s):  
Ioan Pop ◽  
Kohi Naganthran ◽  
Roslinda Nazar

Purpose – The purpose of this paper is to analyse numerically the steady stagnation-point flow of a viscous and incompressible fluid over continuously non-aligned stretching or shrinking surface in its own plane in a water-based nanofluid which contains three different types of nanoparticles, namely, Cu, Al2O3 and TiO2. Design/methodology/approach – Similarity transformation is used to convert the system of boundary layer equations which are in the form of partial differential equations into a system of ordinary differential equations. The system of similarity governing equations is then reduced to a system of first-order differential equations and solved numerically using the bvp4c function in Matlab software. Findings – Unique solution exists when the surface is stretched and dual solutions exist as the surface shrunk. For the dual solutions, stability analysis has revealed that the first solution (upper branch) is stable and physically realizable, while the second solution (lower branch) is unstable. The effect of non-alignment is huge for the shrinking surface which is in contrast with the stretching surface. Practical implications – The results obtained can be used to explain the characteristics and applications of nanofluids, which are widely used as coolants, lubricants, heat exchangers and micro-channel heat sinks. This problem also applies to some situations such as materials which are manufactured by extrusion, production of glass-fibre and shrinking balloon. In this kind of circumstance, the rate of cooling and the stretching/shrinking process play an important role in moulding the final product according to preferable features. Originality/value – The present results are original and new for the study of fluid flow and heat transfer over a stretching/shrinking surface for the problem considered by Wang (2008) in a viscous fluid and extends to nanofluid by using the Tiwari and Das (2007) model.


2016 ◽  
Vol 138 (12) ◽  
Author(s):  
M. M. Rahman

In this paper, we investigate the effects of second-order slip and magnetic field on the nonlinear mixed convection stagnation-point flow toward a vertical permeable stretching/shrinking sheet in an upper convected Maxwell (UCM) fluid with variable surface temperature. Numerical results are obtained using the bvp4c function from matlab for the reduced skin-friction coefficient, the rate of heat transfer, the velocity, and the temperature profiles. The results indicate that multiple (dual) solutions exist for a buoyancy opposing flow for certain values of the parameter space irrespective to the types of surfaces whether it is stretched or shrinked. It is found that an applied magnetic field compensates the suction velocity for the existence of the dual solutions. Depending on the parametric conditions; elastic parameter, magnetic field parameter, first- and second-order slip parameters significantly controls the flow and heat transfer characteristics. The illustrated streamlines show that for upper branch solutions, the effects of stretching and suction are direct and obvious as the flow near the surface is seen to suck through the permeable sheet and drag away from the origin of the sheet. However, aligned but reverse flow occurs for the case of lower branch solutions when the mixed convection effect is less significant.


Processes ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 14 ◽  
Author(s):  
A. Zaib ◽  
Umair Khan ◽  
Ilyas Khan ◽  
Asiful H. H. Seikh ◽  
El-Sayed M. M. Sherif

Entropy generation and dual solutions are rarely studied in the literature. An analysis is attempted here. More exactly, the present paper looks at the impact of radiation of a micropolar fluid on mixed convective flow containing the titanium alloy Ti6Al4V nanoparticle along with a Riga plate. The study of dual-nature solution for the entropy generation along a Riga surface was not being explored in the literature; therefore, the current model focuses on the dual solutions of this complex nature model. Riga surface is identified as an actuator of electromagnetic in which electrodes are accumulated alternatively. This array produces the behavior of electromagnetic hydrodynamic in the flow field. The transmuted leading equations were worked out through the formula of 3-stage Lobatto IIIA. Influences of exercising enormous parameters on temperature distribution, velocity, and micro rotation fields are portrayed and argued. More than one solution is achieved in opposing flow, while in the phenomenon of assisting flow result is unique. Moreover, due to the micropolar parameter, the separation of the boundary layer is decelerating. It is determined that the entire structure produces the dual-nature solution of the phenomenon of stagnation point flow, and the temperature profile behavior shows the significant enhancement in the thermal conductivity due to the addition of the nanoparticle. The results exposed that liquid velocity is enhanced, and micro rotation is decelerated, by improving the values of Hartmann numbers in both solutions, whereas the temperature field is decelerated in the first solution and accelerated in the second solution.


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