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

Buongiorno-Darcy model

Leony Tham, Roslinda Mohd. Nazar, Ioan Pop

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23 Citations (Scopus)

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 languageEnglish
Pages (from-to)21-33
Number of pages13
JournalInternational Journal of Thermal Sciences
Volume84
DOIs
Publication statusPublished - 2014

Fingerprint

Mixed convection
circular cylinders
Circular cylinders
Porous materials
Boundary layers
convection
Thermophoresis
Heating
Boundary layer flow
Brownian movement
Buoyancy
Partial differential equations
boundary layers
Mathematical models
thermophoresis
Heat transfer
Cooling
boundary layer separation
Lewis numbers
heating

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

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title = "Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nanofluid: Buongiorno-Darcy model",
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.",
keywords = "Boundary layer, Buongiorno-Darcy model, Horizontal circular cylinder, Mixed convection, Nanofluid, Porous medium",
author = "Leony Tham and {Mohd. Nazar}, Roslinda and Ioan Pop",
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T1 - Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nanofluid

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AU - Tham, Leony

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AU - Pop, Ioan

PY - 2014

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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.

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