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Dive into the research topics where Leony Tham is active.

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Featured researches published by Leony Tham.


International Journal of Numerical Methods for Heat & Fluid Flow | 2012

Mixed convection boundary layer flow from a horizontal circular cylinder in a nanofluid

Leony Tham; Roslinda Nazar; Ioan Pop

Purpose – The purpose of this paper is to study the steady mixed convection boundary layer flow of a nanofluid past a horizontal circular cylinder in a stream flowing vertically upwards for both cases of a heated and cooled cylinder.Design/methodology/approach – The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite‐difference scheme known as the Keller‐box method. This method is very efficient for solving boundary layer problems.Findings – The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the parameters, namely the nanoparticle volume fraction φ and the mixed convection parameter λ at Prandtl number Pr=1 and 6.2. Three different types of nanoparticles considered are Cu, Al2O3 and TiO2 by using water‐based fluid with Pr=6.2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction φ increases, the skin friction coefficient and heat transfer rate at the surface a...


Journal of Heat Transfer-transactions of The Asme | 2013

Steady Mixed Convection Flow on a Horizontal Circular Cylinder Embedded in a Porous Medium Filled by a Nanofluid Containing Gyrotactic Micro-Organisms

Leony Tham; Roslinda Nazar; Ioan Pop

In this paper, the steady mixed convection boundary layer flow past a horizontal circular cylinder with a constant surface temperature embedded in a porous medium saturated by a nanofluid containing both nanoparticles and gyrotactic micro-organisms in a stream flowing vertically upwards for both cases of a heated and cooled cylinder is numerically studied. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. By considering the governing parameters, namely, the mixed convection parameter λ, the bioconvection Lewis number Lb, the traditional Lewis number Le, the bioconvection Peclet number Pb, the buoyancy ratio Nr, the bioconvection Rayleigh number Rb, the Brownian motion Nb, and the thermophoresis Nt, the numerical results are obtained and discussed for the skin friction coefficient, the local Nusselt number, the local Sherwood number, the local density number of the motile micro-organisms as well as the velocity, temperature, nanoparticle volume fraction, and density motile micro-organisms profiles


Physica Scripta | 2011

Mixed convection boundary-layer flow about an isothermal solid sphere in a nanofluid

Leony Tham; Roslinda Nazar; I Pop

The steady mixed convection boundary-layer flow of a nanofluid about a solid sphere with constant surface temperature has been studied for cases of both assisting and opposing flows. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme known as the Keller-box method. The solutions for the flow and heat-transfer characteristics are evaluated numerically for various values of the parameters, namely the nanoparticle volume fraction and the mixed convection parameter λ at Prandtl numbers Pr=0.7 and 6.2. The three different types of nanoparticles considered are Al2O3, Cu and TiO2, using water-based fluid with Pr=6.2. It is found that for each particular nanoparticle, as the nanoparticle volume fraction increases, the skin friction coefficient and the heat-transfer rate at the surface also increase. This leads to an increase in the value of the mixed convection parameter λ, which at first gives no separation.


PROCEEDINGS OF THE 3RD INTERNATIONAL CONFERENCE ON MATHEMATICAL SCIENCES | 2014

Mixed convection flow about a solid sphere with constant heat flux embedded in a porous medium filled by a nanofluid: Buongiorno-Darcy model

Leony Tham; Roslinda Nazar; Ioan Pop

The laminar mixed convection boundary layer flow about a solid sphere in a nanofluid, which is maintained at a constant surface heat flux, has been studied via the nanofluid Buongiorno model and porous medium Darcy model for both cases of a heated and cooled sphere. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme known as the Keller box method. The solutions for the flow and heat transfer characteristics are evaluated numerically and studied for various values of the governing parameters, namely the Brownian motion parameter, thermophoresis parameter and mixed convection parameter. It is found that the boundary layer separates from the sphere for some negative values of the mixed convection parameter (opposing flow), and increasing the mixed convection parameter delays the boundary layer separation and the separation can be completely suppressed for sufficiently large values of the mixed convection parameter.


PROCEEDINGS OF THE 20TH NATIONAL SYMPOSIUM ON MATHEMATICAL SCIENCES: Research in Mathematical Sciences: A Catalyst for Creativity and Innovation | 2013

Numerical solutions of mixed convection flow on a solid sphere embedded in a porous medium filled by a nanofluid containing gyrotactic microorganisms

Leony Tham; Roslinda Nazar; Ioan Pop

In this paper, the steady mixed convection boundary layer flow over a solid sphere with a constant surface temperature embedded in a porous medium saturated by a nanofluid containing both nanoparticles and gyrotactic microorganisms in a stream flowing vertically upwards for both cases of a heated and cooled sphere, is numerically studied. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. By considering the governing parameters, namely the mixed convection parameter λ, the bioconvection Lewis number Lb, the traditional Lewis number Le, the bioconvection Peclet number Pb, the buoyancy ratio Nr, the bioconvection Rayleigh number Rb, the Brownian motion Nb and the thermophoresis Nt, the numerical results are obtained and discussed for the local density number of the motile microorganisms as well as the velocity, temperature, nanoparticle volume fraction and density motile microorganisms profiles.


Proceedings of CHT-12. ICHMT International Symposium on Advances in Computational Heat Transfer. July 1-6, 2012, Bath, England | 2012

Mixed convection flow over a horizontal circular cylinder with a constant surface heat flux in a nanofluid

Leony Tham; Roslinda Nazar; Ioan Pop

The steady laminar mixed convection boundary layer flow from a horizontal circular cylinder in a nanofluid embedded in a porous medium, which is maintained at a constant surface heat flux, has been studied by using the Buongiorno–Darcy nanofluid model 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 known as the Keller box method. The solutions for the flow and heat transfer characteristics are evaluated numerically and studied for various values of the governing parameters, namely the Lewis number, Brownian number, mixed convection parameter, buoyancy ratio parameter and thermophoresis parameter. It is also found that the boundary layer separation occurs at the opposing fluid flow, that is when the mixed convection parameter is negative. It is also observed that increasing the mixed convection parameter delays the boundary layer separation and the separation can be completely suppressed for sufficiently large values of the mixed convection parameter. The Brownian and buoyancy ratio parameters appear to affect the fluid flow and heat transfer profiles.


International Journal of Heat and Mass Transfer | 2013

Mixed convection flow over a solid sphere embedded in a porous medium filled by a nanofluid containing gyrotactic microorganisms

Leony Tham; Roslinda Nazar; Ioan Pop


International Journal of Thermal Sciences | 2014

Mixed convection flow from a horizontal circular cylinder embedded in a porous medium filled by a nanofluid: Buongiorno–Darcy model

Leony Tham; Roslinda Nazar; Ioan Pop


Sains Malaysiana | 2012

Mixed convection flow about a solid sphere embedded in a porous medium filled with a nanofluid

Leony Tham; Roslinda Nazar


Applied Water Science | 2017

Effect of process variables interaction on simultaneous adsorption of phenol and 4-chlorophenol: statistical modeling and optimization using RSM

Kwok-Yii Leong; Sylvia See; Jun-Wei Lim; Mohammed J.K. Bashir; Choon Aun Ng; Leony Tham

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Roslinda Nazar

National University of Malaysia

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Jun-Wei Lim

Universiti Teknologi Petronas

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Mohammed J.K. Bashir

Universiti Tunku Abdul Rahman

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Anita Ramli

Universiti Teknologi Petronas

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Choon Aun Ng

Universiti Tunku Abdul Rahman

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Chung-Yiin Wong

Universiti Teknologi Petronas

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Kwok-Yii Leong

Universiti Sains Malaysia

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Man-Kee Lam

Universiti Teknologi Petronas

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Mohd Zuki Salleh

Universiti Malaysia Pahang

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