Axisymmetric mixed convective stagnation-point flow of a nanofluid over a vertical permeable cylinder by Tiwari-Das nanofluid model

作者：Dinarvand Saeed; Hosseini Reza; Pop Loan

来源：Powder Technology, 2017, 311: 147-156.

DOI：10.1016/j.powtec.2016.12.058

• Stagnation-point flow
• Axisymmetric mixed convection
• Vertical cylinder
• Nanofluids
• Nanoparticle volume fraction
• Tiwari-Das nanofluid model
• HAM

In this article, the steady axisymmetric mixed convective stagnation-point flow of an incompressible electrically conducting nanofluid over a vertical permeable circular cylinder in the presence of transverse magnetic field is investigated. The mathematical model has been formulated based on Tiwari-Das nanofluid model. In this study, the water as the base fluid and three different types of nanoparticles; copper, aluminum oxide (alumina) and titanium dioxide (titania) are considered. Using appropriate transformations, the system of partial differential equations is transformed into an ordinary differential system of two equations, which is solved analytically by the well-known homotopy analysis method (HAM) and numerically using the fourth-order Runge-Kutta method with shooting technique. The present analytical and numerical simulations agree closely with the previous studies in the especial cases. The effects of the five key thermophysical parameters governing the flow; the nano particle volume fraction (phi), the magnetic parameter (M), the Wall permeability parameter (V-W), the mixed convection parameter (lambda) and the curvature parameter (gamma) on dimensionless velocity and temperature distributions, skin friction coefficient and local Nusselt number are presented graphically and discussed in details. Our results demonstrate that, the enhancement of heat transfer is a function of particle concentration, small fraction of metallic particles leading to significant changes in both skin friction coefficient and local Nusselt number. The results illustrate that selecting alumina and copper as the nanoparticle leads to the minimum and maximum amounts of skin friction coefficient value, and also copper and titania nanoparticles have the largest and lowest local Nusselt number. In addition, our computation shows that the curvature parameter has a strong additive effect on the skin friction coefficient and local Nusselt number. Moreover, it is observed that the highest velocity and thermal boundary layer thickness are related to the opposing flow, while the smallest one is for assisting flow.

• 出版日期2017-4-15