### Abstract

Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nanofluid has been studied for both cases of a heated and cooled cylinder using the Buongiorno-Darcy mathematical nanofluid model. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the constant mixed convection parameter λ, the traditional Lewis number Le, the buoyancy ratio parameter Nr, the Brownian motion parameter Nb and the thermophoresis parameter Nt. It is found that in the present case of the porous medium flow, the separation is always suppressed at negative values of λ. When λ changes from -2.1 to 0, one has a "heating" of the cylinder, but a heating in the negative range of λ (λ < 0). However, for a clear (Newtonian) fluid, Merkin (1977) found that heating the cylinder (λ > 0) delays the separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely at a positive value of λ, somewhere between 0.88 and 0.89. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ < 0) there will not be a boundary layer on the cylinder.

Original language | English |
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Pages (from-to) | 21-33 |

Number of pages | 13 |

Journal | International Journal of Thermal Sciences |

Volume | 84 |

DOIs | |

Publication status | Published - 2014 |

### Fingerprint

### Keywords

- Boundary layer
- Buongiorno-Darcy model
- Horizontal circular cylinder
- Mixed convection
- Nanofluid
- Porous medium

### ASJC Scopus subject areas

- Engineering(all)
- Condensed Matter Physics

### Cite this

**Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nanofluid : Buongiorno-Darcy model.** / Tham, Leony; Mohd. Nazar, Roslinda; Pop, Ioan.

Research output: Contribution to journal › Article

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TY - JOUR

T1 - Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nanofluid

T2 - Buongiorno-Darcy model

AU - Tham, Leony

AU - Mohd. Nazar, Roslinda

AU - Pop, Ioan

PY - 2014

Y1 - 2014

N2 - Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nanofluid has been studied for both cases of a heated and cooled cylinder using the Buongiorno-Darcy mathematical nanofluid model. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the constant mixed convection parameter λ, the traditional Lewis number Le, the buoyancy ratio parameter Nr, the Brownian motion parameter Nb and the thermophoresis parameter Nt. It is found that in the present case of the porous medium flow, the separation is always suppressed at negative values of λ. When λ changes from -2.1 to 0, one has a "heating" of the cylinder, but a heating in the negative range of λ (λ < 0). However, for a clear (Newtonian) fluid, Merkin (1977) found that heating the cylinder (λ > 0) delays the separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely at a positive value of λ, somewhere between 0.88 and 0.89. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ < 0) there will not be a boundary layer on the cylinder.

AB - Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nanofluid has been studied for both cases of a heated and cooled cylinder using the Buongiorno-Darcy mathematical nanofluid model. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the constant mixed convection parameter λ, the traditional Lewis number Le, the buoyancy ratio parameter Nr, the Brownian motion parameter Nb and the thermophoresis parameter Nt. It is found that in the present case of the porous medium flow, the separation is always suppressed at negative values of λ. When λ changes from -2.1 to 0, one has a "heating" of the cylinder, but a heating in the negative range of λ (λ < 0). However, for a clear (Newtonian) fluid, Merkin (1977) found that heating the cylinder (λ > 0) delays the separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely at a positive value of λ, somewhere between 0.88 and 0.89. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ < 0) there will not be a boundary layer on the cylinder.

KW - Boundary layer

KW - Buongiorno-Darcy model

KW - Horizontal circular cylinder

KW - Mixed convection

KW - Nanofluid

KW - Porous medium

UR - http://www.scopus.com/inward/record.url?scp=84901936370&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84901936370&partnerID=8YFLogxK

U2 - 10.1016/j.ijthermalsci.2014.04.020

DO - 10.1016/j.ijthermalsci.2014.04.020

M3 - Article

VL - 84

SP - 21

EP - 33

JO - International Journal of Thermal Sciences

JF - International Journal of Thermal Sciences

SN - 1290-0729

ER -