Sains Malaysiana 41(3)(2012): 345–351

Temperature Dependency on Mixed Convection Boundary Layer Flow Over an

Isoflux Horizontal Circular Cylinder

(Kebersandaran Suhu Terhadap Aliran Lapisan Sempadan bagi Olakan Campuran

ke atas Silinder Bulat Mengufuk Isofluks)

Azizah Mohd Rohni

Pusat Pengajian Sains Kuantitatif, Universiti Utara Malaysia

06010 UUM Sintok, Kedah, Malaysia

Syakila Ahmad* & Ahmad Izani Md. Ismail

School of Mathematical Sciences, Universiti Sains Malaysia

11800 Penang, Malaysia

Ioan Pop

Faculty of Mathematics, University of Cluj, R-400082 Cluj

CP 253 Romania

Diserahkan: 28 Januari 2011 / Diterima: 19 September 2011

ABSTRACT

Steady laminar mixed convection boundary layer flow past a horizontal circular cylinder with constant wall heat flux, immersed in a viscous and incompressible fluid of temperature-dependent viscosity is considered in this study. The governing partial differential equations were transformed using non-similar transformation and then solved numerically by an implicit finite-difference scheme known as the Keller-box method. The effects of temperature-dependent viscosity parameter θr on the flow and heat transfer characteristics were examined for various values of Prandtl number, Pr and the mixed convection parameter, λ. It was found that for both assisting and opposing flows, as θr increases, the local skin friction coefficient increases while the wall temperature decreases for air but for water, the local skin friction coefficient decreases then slightly increases while temperature decreases.

Keywords: Boundary layer; horizontal circular cylinder; isoflux; mixed convection; temperature dependency

ABSTRAK

Aliran lapisan sempadan mantap berlamina bagi olakan campuran ke atas silinder bulat mengufuk dengan fluks haba malar, direndam dalam bendalir likat tak mampat dengan kelikatan bersandar-suhu dipertimbangkan. Persamaan menakluk dalam bentuk persamaan pembezaan separa dijelmakan menggunakan penjelmaan tak serupa dan kemudiannya diselesaikan menggunakan skim beza terhingga tersirat yang dikenali sebagai kaedah kotak Keller. Kesan parameter kelikatan bersandar-suhu θr ke atas ciri-ciri aliran dan pemindahan haba dikaji bagi pelbagai nilai nombor Prandtl, Pr dan parameter olakan campuran, λ. Didapati untuk kedua-dua aliran membantu dan menentang, apabila θr meningkat, pekali geseran kulit meningkat sementara suhu dinding menurun bagi udara tetapi bagi air, pekali geseran kulit menurun kemudian meningkat sedikit sementara suhu dinding menurun.

Kata kunci: Isofluks; kebersandaran suhu; lapisan sempadan; olakan campuran; silinder bulat mengufuk.

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*Pengarang untuk surat-menyurat; email: syakilaahmad@usm.my