C. Shi¹, C. Wang¹, T. Wei^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.2, pp. 71-92, 2012, DOI:10.3970/cmes.2012.086.071

Abstract In this paper, we consider a typical ill-posed inverse heat source problem, that is, we determine a space-dependent heat source term in a multi-dimensional heat equation from a pair of Cauchy data on a part of boundary. By a simple transformation, the inverse heat source problem is changed into a Cauchy problem of a homogenous heat conduction equation. We use the method of fundamental solutions (MFS) coupled with the Tikhonov regularization technique to solve the ill-conditioned linear system of equations resulted from the MFS discretization. The generalized cross-validation rule for determining the regularization parameter is More >

Wei-Chung Tien¹, Yue-Tzu Yang¹, Cha’o-Kuang Chen^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.5, pp. 447-462, 2012, DOI:10.3970/cmes.2012.085.447

Abstract Both buoyancy effects of thermal and mass diffusion in the natural convection flow about a vertical plate are considered in this paper. The non-linear coupled differential governing equations for velocity, temperature and concentration fields are solved by using the homotopy analysis method. Without the need of iteration, the obtained solution is in the form of an infinite power series which indicates those series have high accuracy when comparing it with other-generated by the traditional method. The impact of the Prandtl number, Schmidt number and the buoyancy parameter on the flow are widely discussed in detail. More >

C.S. Nor Azwadi¹, N.I.N. Izual²

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.6, pp. 559-574, 2012, DOI:10.3970/cmes.2012.084.559

Abstract Natural convection in a differentially heated enclosure plays vital role in engineering applications such as nuclear reactor, electronic cooling technologies, roof ventilation, etc. The developed thermal flow patterns induced by the density difference are expected to be critically dependence on the inclination angles of the cavity. Hence, thermal and fluid flow pattern inside a differentially heated side enclosure walls with various inclination angles have been investigated numerically using the mesoscale lattice Boltzmann scheme. Three different dimensionless Rayleigh numbers were used, and a dimensionless Prandtl number of 0.71 was set to simulate the circulation of air More >

Ridha Djebali^1,2, Mohamed ElGanaoui³, Taoufik Naffouti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.6, pp. 499-527, 2012, DOI:10.3970/cmes.2012.084.499

Abstract A thermal lattice Boltzmann model for incompressible flow is developed and extended to investigate the natural convection flow in porous media under the effect of uniform magnetic field. The study shows that the flow behaviour is various parameters dependent. The Rayleigh number (Ra), Hartmann number (Ha), Darcy number (Da) and the medium inclination angle from the horizontal (Φ), the magnetic field orientation (ψ) and the medium porosity (ε) effects are carried out in wide ranges encountered in industrial and engineering applications. It was found that the flow and temperature patterns change significantly when varying these parameters. To confirm More >

Wei-Chung Tien¹, Yue-Tzu Yang¹, Cha’o-Kuang Chen^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.84, No.2, pp. 155-170, 2012, DOI:10.3970/cmes.2012.084.155

Abstract In this paper, the homotopy analysis method is applied to analyze the heat transfer of the oscillating base temperature processes occurring in a convective rectangular fin with variable thermal conductivity. This method is a powerful and easy-to-use tool for non-linear problems and it provides us with a simple way to adjust and control the convergence region of solution series. Without the need of iteration, the obtained solution is in the form of an infinite power series and the results indicated that the series has high accuracy by comparing it with those generated by the complex More >

W. A. El-Askary, A. Abdel-Fattah

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 425-458, 2012, DOI:10.3970/cmes.2012.083.425

Abstract In the present paper, experimental and numerical studies of heat transfer and the frictional head loss of turbulent flow in a duct with a heated upper surface are performed. Four different arrangements are considered (case 1: without baffles, case 2: one perforated baffle on the upper wall and one solid baffle on the lower wall, case 3: one perforated baffle on the upper wall and one perforated baffle on the lower wall and case 4: two perforated baffles on the upper wall). A numerical code developed by the present authors is simultaneously presented including four… More >

M.R. Myers¹, A.B. Jorge², D.E. Yuhas³, D.G. Walker¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.3, pp. 221-248, 2012, DOI:10.3970/cmes.2012.083.221

Abstract An adaptive extended Kalman filter is developed and investigated for a transient heat transfer problem in which a high heat flux spot source is applied on one side of a thin plate and ultrasonic pulse time of flight is measured between spatially separated transducers on the opposite side of the plate. The novel approach is based on the uncertainty in the state model covariance and leverages trends in the extended Kalman filter covariance to drive changes to the state model covariance during convergence. This work is an integral part of an effort to develop a… More >

Walid Hassen¹, Mohamed Naceur Borjini², Habib Ben Aissia¹

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.4, pp. 381-396, 2012, DOI:10.3970/fdmp.2012.008.381

Abstract In this work we consider the problem related to the electro-thermo-convection of a dielectric fluid in a rectangular enclosure placed between two electrodes. This layer is subjected simultaneously to the injection of electric charges and to a thermal gradient. The influence of the electric Rayleigh number (200 - 1000) on the structure of the flow, the density of electric charge and heat transfer is investigated. An oscillatory flow is observed and discussed in detail. More >

F.Z. Ferahta^1,2, S. Bougoul¹, M. Médale², C. Abid²

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 339-352, 2012, DOI:10.3970/fdmp.2012.008.339

Abstract A numerical study is carried out to evaluate the thermal performances of a solar collector. As it is well known, that the thermal losses of such systems are mainly of a convective nature, the study is concentrated in particular on the features of natural convection that is activated in the air domain delimited by the upper glass and the lower absorber of the solar collector. The efficiency of such a system depends essentially on both the temperature difference and the distance between the absorber and the glass. Since the temperature difference remains an uncontrolled variable More >

A. Khourchafi¹, M. El Alami^2,3, M. Najam², M. Belhaq⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.3, pp. 323-338, 2012, DOI:10.3970/fdmp.2012.008.323

Abstract A spectral radiation study has been carried out in the framework of a statistical narrow-band model based on an inverse-tailed exponential law and the socalled P1 approximation. This new spectral formulation, which may be also regarded as a grey band formulation with a local absorption coefficient, leads to two implementation methods: a non correlated form in which the averaged formulation of the P1 approximation does not take into account the correlation between fundamental quantities and a pseudo-correlated variant consisting basically of a technique for improving the anisotropy of the radiative intensity. Real gases (H₂O, CO₂) are More >