M. A. Alim

Modeling of mixed convective heat transfer utilizing nanofluid in a double lid-driven chamber with internal heat generation

Purpose – This work is focused on the numerical modeling of mixed convective heat transfer in a double lid-driven cavity filled with water-CuO nanofluid in the presence of internal heat generation. The paper aims to discuss these issues. Design/methodology/approach – The flow field is modeled using a generalized form of the momentum and energy equations. Discretization of the governing equations is achieved using the penalty finite element scheme based on the Galerkin method of weighted residuals. Findings – The effects of pertinent parameters such as the internal heat generation parameter (Q), the Richardson number (Ri) and the solid volume fraction () on the flow and heat transfer characteristics are presented and discussed. The obtained results depict that the Richardson number plays a significant role on the heat transfer characterization within the triangular wavy chamber. Also, the present results show that an increase in volume fraction has a significant effect on the flow patterns. Research limita...

Heat Transfer and Collector Efficiency through a Direct Absorption Solar Collector with Radiative Heat Flux Effect

This article presents a numerical visualization of heat transport for forced convective heat transfer by a two-dimensional heat function formulation through a direct absorption solar collector (DASC) filled with water-copper nanofluid. The penalty finite element method is used to solve nonlinear partial differential equations, and the numerical results are presented for variations in the radiative heat flux, Prandtl number, particle diameter, and solid volume fraction of the nanoparticle. The rate of heat transfer, thermal efficiency, mean entropy generation, and Bejan number are strongly dependent on certain parameters. It is observed that the radiative heat flux variation decreases the mean heat transfer, but increases the collector efficiency and entropy generation for nanofluids more than that for pure water. According to the results obtained from this study, under similar operating conditions, DASC is found to have higher efficiency than a flat-plate solar collector (FPSC). Generally, a DASC performs better than a flat-plate collector; however, much better designed flat-plate collectors might be able to match or outperform the efficiency of a nanofluid-based DASC under certain conditions.

A comprehensive study including monitoring, assessment of health effects and development of a remediation method for chromium pollution

Chromium (Cr) pollution caused by wastewater from tanneries is a worldwide environmental problem. To develop a countermeasure, we performed a comprehensive study using Hazaribagh, the tannery area in Dhaka City, Bangladesh, as a model. Our environmental monitoring indicated that the soluble form of Cr, but not barium or arsenic, in Buriganga River is derived from Hazaribagh. Our chemical analysis next showed that Cr, the primary pollutant in canal water at Hazaribagh, consisted of ≤0.7 μM hexavalent Cr [Cr(VI)] and ≤1705 μM trivalent Cr [Cr(III)]. Our biological study then showed that coexposure to Cr(VI) and Cr(III) at possible ratios in canal water at Hazaribagh synergistically promotes transforming activity of human non-tumorigenic HaCaT keratinocytes with activated MEK/ERK and AKT. Our environmental engineering study finally indicated that a magnesium and iron-based hydrotalcite-like compound (MF-HT), our original depurative, can maximally adsorb 9.0 mg/g Cr(VI) and 1041 mg/g Cr(III). Our results suggested the importance of removal of Cr(III) as well as Cr(VI) by showing that Cr(III), which is generally recognized as a chemical with low toxicity, synergistically promoted carcinogenicity of a low level of Cr(VI). Therefore, we propose the use of our original high-efficient and low-cost depurative as a countermeasure to address the worldwide problem of environmental Cr pollution.

Magnetohydrodynamic boundary layer nanofluid flow and heat transfer over a stretching surface

The present study is performed to investigate the effect of unsteadiness, stretching ratio, Brownian motion, thermophoresis and magnetic parameter on boundary layer such as momentum, thermal and nanoparticle concentration. In this respect we have considered the magnetohydrodynamic (MHD) unsteady boundary layer nanofluid flow and heat – mass transfer over a stretching surface. The dimensionless governing equations are unsteady, two-dimensional coupled and non-linear ordinary differential equations. The numerical solution is taken by applying the Nachtsgeim-Swigert shooting iteration technique along with Runge-Kutta integration scheme. The effects of various dimensionless parameters on velocity, temperature and nanoparticle concentration are discussed numerically and shown graphically. Therefore, from the figures it is observed that the results of velocity profile increases for increasing values of magnetic parameter and unsteadiness parameter but decreases for stretching ratio parameter, the temperature pr...

Unsteady boundary layer nanofluid flow and heat transfer along a porous stretching surface with magnetic field

The present study is performed to find the similarity solution like Blasius solution and also analyzed the effect of various dimensionless parameters on the momentum, thermal and nanoparticle concentration. In this respect we have considered the magnetohydrodynamic (MHD) unsteady boundary layer nanofluid flow and heat – mass transfer along a porous stretching surface. So the governing partial differential equations are transformed to ordinary differential equations by using similarity transformations. The numerical solution is taken by applying the Nachtsgeim-Swigert shooting iteration technique along with Runge-Kutta integration scheme. The effects of various dimensionless parameters on velocity, temperature and nanoparticle concentration are discussed numerically and shown graphically. Therefore, from the figures it is observed that the results of velocity profile increases for increasing values of unsteadiness parameter, permeability parameter and stretching ratio parameter but there is no effect for magnetic parameter, the temperature profile decreases for increasing values of Brownian motion, unsteadiness, thermophoresis and stretching ratio but increases for magnetic parameter, the nanoparticle concentration decreases for increasing values of unsteadiness parameter, thermophoresis parameter, suction parameter, stretching ratio parameter and Lewis number but increases for magnetic parameter and Brownian motion parameter. For validity and accuracy the present results are compared with previously published work and found to in good agreement.The present study is performed to find the similarity solution like Blasius solution and also analyzed the effect of various dimensionless parameters on the momentum, thermal and nanoparticle concentration. In this respect we have considered the magnetohydrodynamic (MHD) unsteady boundary layer nanofluid flow and heat – mass transfer along a porous stretching surface. So the governing partial differential equations are transformed to ordinary differential equations by using similarity transformations. The numerical solution is taken by applying the Nachtsgeim-Swigert shooting iteration technique along with Runge-Kutta integration scheme. The effects of various dimensionless parameters on velocity, temperature and nanoparticle concentration are discussed numerically and shown graphically. Therefore, from the figures it is observed that the results of velocity profile increases for increasing values of unsteadiness parameter, permeability parameter and stretching ratio parameter but there is no effect for m...

Optimization of mixed convection in a lid-driven porous square cavity with internal elliptic shape adiabatic block and linearly heated side walls

The physical model considered here is a lid-driven porous square cavity with internal elliptic shape adiabatic block and linearly heated side walls. The top moving wall is well cold and set with uniform velocity. The bottom moving wall heated, linearly heated side walls and inside the elliptic shape adiabatic. The relevant parameters in the present study are Darcy number Da = 10−5-10−3, Grashof number Gr = 103-105, Reynolds number Re = 1-102 and Prandtl number Pr = 0.7. The isotherms are also almost symmetric at small Re with higher Gr (Gr = 105) and Da (Da = 10−3) and natural convection is found to be dominant whereas the isotherms are compressed near the left and bottom walls at higher Re for linearly heated side walls. The solution of these governing equations is obtained numerically with the finite element approach using the Galerkin method of weighted residuals. Results are presented in the form of streamlines, isotherms, Local Nusselt number, average Nusselt number, velocity and temperature for the ...

Numerical simulation of heat transfer and fluid flow with lid-driven square cavity and discrete source-sink pairs

In this paper heat transfer and fluid flow in a two-dimensional lid-driven square cavity with discrete source-sink is studied. A finite element method is used for solving the governing equations. The parametric studies are Darcy number in the range of 10−5 to 10−1, Grashof number in the range of 103 to 105, Reynolds number constant at 100 and Prandtl number constant at 0.71. Galerkin weighted residual method is used to perform numerical solutions. The streamlines, isotherms, average Nusselt number, and average temperature of the fluid in the enclosure are presented for the dimensionless parameters. It is found that the heat transfer rate is decreased for decreasing of Darcy number.

Numerical simulation of natural convection in a rectangular cavity with triangles of different orientation in presence of magnetic field

Free convection flow and heat transfer in a rectangular cavity in presence of magnetic field with one heated side triangle in the enclosure is investigated numerically. A finite element analysis is performed to investigate the effects of uniform heating and is also used for solving the Navier-Stokes and Energy balance equations. The horizontal bottom wall is divided into three equal sections. The middle section of the horizontal bottom wall and one of the triangles in the enclosure were kept temperature at Th. The other two parts of the horizontal bottom wall and the other two sides of the triangle were kept thermal insulation while the left and right vertical walls and the top wall of the cavity were maintained constant temperature Tc with Th>Tc. The physical problems are represented mathematically by different sets of governing equations along with corresponding boundary conditions. The dimensionless Parameters in the equations are performed for magnetic parameter Hartmann number (Ha), Rayleigh number (...

Numerical simulation of MHD free convection flow in a differentially heated square enclosure with tilted obstacle

A numerical study has been carried out to analyze the flow and heat transfer characteristics due to the effects of magnetohydrodynamic free convection flow in a differentially heated enclosure having a hot tilted square block. The vertical and horizontal walls of the cavity are non-uniformly heated while the walls of the tilted block are uniformly heated. The basic partial differential equations of the physical problem are solved numerically using finite element technique along with Galerkin’s weighted residual simulation. Calculations have been performed for different values of buoyancy parameter (102 ≤ Ra ≤ 105) and magnetic field parameter (0 ≤ Ha ≤ 60) and obtained results are illustrated in terms of streamlines, isotherms, average Nusselt number and average temperature. The results show that the flow pattern and temperature distributions affected noticeably for the effect of aforementioned parameters. In addition, an increase in average Nusselt number is found for the whole range of Rayleigh number and average temperature decreased for increasing Rayleigh number. Comparison between the obtained results and the previously published results on the basis of special case is a good agreement.

A numerical study of magneto-hydrodynamic free convection in a square cavity with heated elliptic block

The problem of Magneto-hydrodynamic (MHD) field on buoyancy-driven free convection heat transfer in a square cavity with heated elliptic block at the centre has been investigated in this work. The governing differential equations are solved by using finite element method (Galerkin weighted residual method). The lower wall is adiabatic. The left wall is kept at heated Th. The right and upper wall is kept at cold Tc respectively. Also all the wall are assumed to be no-slip condition. The study is performed for different Rayleigh and Hartmann numbers. A heated elliptic block is located at the centre of the cavity. The object of this study is to describe the effects of MHD on the field of buoyancy-driven and flow in presence of such heated block by visualization of graph. The results are illustrated with the streamlines, isotherms, velocity and temperature fields as well as local Nusselt number.