### 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. 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 nanoparticle volume fraction φ and the mixed convection parameter λ. Three different types of nanoparticles are considered, namely Cu, Al_{2}O_{3} and TiO_{2}. It is found that for each particular nanoparticle, as the nanoparticle volume fraction φ increases, the magnitude of the skin friction coefficient decreases, and this leads to an increase in the value of the mixed convection parameter λ which first produces no separation. On the other hand, it is also found that of all the three types of nanoparticles considered, for any fixed values of φ and λ, the nanoparticle Cu gives the largest values of the skin friction coefficient followed by TiO_{2} and Al_{2}O_{3}. Finally, it is worth mentioning that heating the cylinder (λ > 0) delays separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely. 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 |
---|---|

Pages (from-to) | 517-536 |

Number of pages | 20 |

Journal | Transport in Porous Media |

Volume | 86 |

Issue number | 2 |

DOIs | |

Publication status | Published - Jan 2011 |

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### Keywords

- Boundary layer
- Horizontal cylinder
- Mixed convection
- Nanofluid
- Porous medium

### ASJC Scopus subject areas

- Chemical Engineering(all)
- Catalysis

### Cite this

*Transport in Porous Media*,

*86*(2), 517-536. https://doi.org/10.1007/s11242-010-9637-1

**Mixed Convection Boundary Layer Flow from a Horizontal Circular Cylinder Embedded in a Porous Medium Filled with a Nanofluid.** / Mohd. Nazar, Roslinda; Tham, L.; Pop, I.; Ingham, D. B.

Research output: Contribution to journal › Article

*Transport in Porous Media*, vol. 86, no. 2, pp. 517-536. https://doi.org/10.1007/s11242-010-9637-1

}

TY - JOUR

T1 - Mixed Convection Boundary Layer Flow from a Horizontal Circular Cylinder Embedded in a Porous Medium Filled with a Nanofluid

AU - Mohd. Nazar, Roslinda

AU - Tham, L.

AU - Pop, I.

AU - Ingham, D. B.

PY - 2011/1

Y1 - 2011/1

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. 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 nanoparticle volume fraction φ and the mixed convection parameter λ. Three different types of nanoparticles are considered, namely Cu, Al2O3 and TiO2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction φ increases, the magnitude of the skin friction coefficient decreases, and this leads to an increase in the value of the mixed convection parameter λ which first produces no separation. On the other hand, it is also found that of all the three types of nanoparticles considered, for any fixed values of φ and λ, the nanoparticle Cu gives the largest values of the skin friction coefficient followed by TiO2 and Al2O3. Finally, it is worth mentioning that heating the cylinder (λ > 0) delays separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely. 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. 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 nanoparticle volume fraction φ and the mixed convection parameter λ. Three different types of nanoparticles are considered, namely Cu, Al2O3 and TiO2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction φ increases, the magnitude of the skin friction coefficient decreases, and this leads to an increase in the value of the mixed convection parameter λ which first produces no separation. On the other hand, it is also found that of all the three types of nanoparticles considered, for any fixed values of φ and λ, the nanoparticle Cu gives the largest values of the skin friction coefficient followed by TiO2 and Al2O3. Finally, it is worth mentioning that heating the cylinder (λ > 0) delays separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely. 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 - Horizontal cylinder

KW - Mixed convection

KW - Nanofluid

KW - Porous medium

UR - http://www.scopus.com/inward/record.url?scp=79953175948&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79953175948&partnerID=8YFLogxK

U2 - 10.1007/s11242-010-9637-1

DO - 10.1007/s11242-010-9637-1

M3 - Article

AN - SCOPUS:79953175948

VL - 86

SP - 517

EP - 536

JO - Transport in Porous Media

JF - Transport in Porous Media

SN - 0169-3913

IS - 2

ER -