Documents published in Scipedia

• Numerical study of double diffusive buoyancy forces induced natural convection in a trapezoidal enclosure partially heated from the right sidewall

  M. Gholizadeh, R. Nikbakhti, J. Khodakhah, A. Ghasemi

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  A study of double-diffusive natural convection in a trapezoidal enclosure with a partial heated active right sidewall has been conducted numerically using the finite difference method. The length of the heated active part is equal to half of the inclined wall. Uniform different temperatures and concentrations are imposed along the active parts of the enclosure. The top and bottom boundaries of the enclosure, as well as inactive part of the right sidewall, are being insulated and impermeable. The species diffusivity of the fluid is considered to be constant, but the density varies linearly with the temperature and concentration. Double-diffusive convection for laminar two-dimensional incompressible flow with negligible radiation is expressed in terms of vorticity, temperature or energy, concentration and stream function. A Partial Differential Equation (PDE) technique is adopted to generate regular grid distribution in the physical space. The numerical results are reported for the effect of different heating cases, thermal Grashof numbers, and inclination angles on the contours of streamline, temperature, and concentration. Also, the relevant results for the average Nusselt and Sherwood numbers are demonstrated for several parameters including thermal Grashof number (103⩽GrT⩽106)103⩽GrT⩽106), Lewis number (0.5⩽Le⩽10)0.5⩽Le⩽10), Prandtl number (0.7⩽Pr⩽10)0.7⩽Pr⩽10) at a fixed aspect ratio Ar=1Ar=1 and buoyancy ratio N=-0.2N=-0.2.

  Abstract
  A study of double-diffusive natural convection in a trapezoidal enclosure with a partial heated active right sidewall has been conducted numerically using the finite difference [...]

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• New homotopy perturbation method for system of Burgers equations

  M. Mirzazadeh, Z. Ayati

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this paper, new homotopy perturbation method (NHPM) (Biazar et al., 2007) is applied to obtain solutions of system of Burgers equations. In this method, the solution is considered as an infinite series expansion where it converges rapidly to the exact solution. In order to show the ability and reliability of the method some examples are provided. The results reveal that the method is very effective and simple. The modified method accelerates the rapid convergence of the series solution and reduces the size of work.

  Abstract
  In this paper, new homotopy perturbation method (NHPM) (Biazar et al., 2007) is applied to obtain solutions of system of Burgers equations. In this method, the solution is [...]

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• Large amplitude free vibration of axially loaded beams resting on variable elastic foundation

  A. Mirzabeigy, R. Madoliat

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In the present study, large amplitude free vibration of beams resting on variable elastic foundation is investigated. The Euler–Bernoulli hypothesis and the Winkler model have been applied for beam and elastic foundation, respectively. The beam is axially loaded and is restrained by immovable boundary conditions, which yields stretching during vibrations. The energy method and Hamilton’s principle are used to derive equation of motion, where after decomposition an ordinary differential equation with cubic nonlinear term is obtained. The second order homotopy perturbation method is applied to solve nonlinear equation of motion. An explicit amplitude-frequency relation is achieved from solution with relative error less than 0.07% for all amplitudes. This solution is applied to study effects of variable elastic foundation, amplitude of vibration and axial load on nonlinear frequency of beams with simply supported and fully clamped boundary conditions. Proposed formulation is capable to dealing with any arbitrary distribution of elastic foundation.

  Abstract
  In the present study, large amplitude free vibration of beams resting on variable elastic foundation is investigated. The Euler–Bernoulli hypothesis and the Winkler model [...]

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• New approach method for solving Duffing-type nonlinear oscillator

  H. Mirgolbabaee, S. Ledari, D. Ganji

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this paper attempts have been done to solve nonlinear oscillator by using Akbari–Ganji’s Method (AGM). Solving nonlinear equation is difficult due to its high nonlinearity. This new approach is emerged after comparing the achieved solutions with numerical method and exact solution. Results are presented for different values of amplitude vibration of the problem parameters which would certainly illustrate that this method (AGM) is efficient and has enough accuracy in comparison with other semi analytical and numerical methods. Moreover, results demonstrate that AGM could be applicable through other methods in nonlinear problems with high nonlinearity. Furthermore, convergence problems for solving nonlinear equations by using AGM appear small.

  Abstract
  In this paper attempts have been done to solve nonlinear oscillator by using Akbari–Ganji’s Method (AGM). Solving nonlinear equation is difficult due to its high nonlinearity. [...]

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• LBM simulation of natural convection in an inclined triangular cavity filled with water

  I. Mejri, A. Mahmoudi, M. Abbassi, A. Omri

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  This paper presents a numerical study of natural convection in a triangular cavity filled with water. The horizontal wall is hot, the vertical wall is cold and the inclined wall is insulated. Lattice Boltzmann method (LBM) is applied to solve the coupled equations of flow and temperature fields. This study has been carried out for the pertinent parameters in the following ranges: Rayleigh number varied from Ra = 103 to 106 and the inclination angle between Φ=0°Φ=0° and 315°315°. The effects of Rayleigh numbers and inclination angle on the streamlines, isotherms, Nusselt number are investigated. Results show that the heat transfer rate increases with the increase of Rayleigh number. In addition it is observed that the lower heat transfer rate is obtained for Φ=135°Φ=135°, however, the highest heat transfer is achieved at Φ=0°Φ=0°. The inclination angle greatly influences the heat transfer rate depending on the Rayleigh number.

  Abstract
  This paper presents a numerical study of natural convection in a triangular cavity filled with water. The horizontal wall is hot, the vertical wall is cold and the inclined [...]

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• Buoyancy driven heat transfer in nanofluids due to wall mounted heat source

  S. Malik, A. Nayak

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  This work is focussed on the numerical modeling of mixed convection heat transfer effects in a lid-driven cavity filled with a copper–water nanofluid. A heated wall mounted block with constant heat flux is attached along the vertical wall. The left vertical wall is maintained at higher temperature compared to the right vertical wall and the other (top and bottom) walls are insulated. A finite volume based numerical approach with QUICK scheme is used for the solution of nonlinear governing equations. A computational visualization technique is used to represent the two dimensional results of streamlines, isotherms, average Nusselt number and bulk-average temperature for a wide range of physical parameters, namely Reynolds number, Rayleigh number and solid volume fraction. The effective fluid flow and heat transfer variation are analyzed by placing the heated mounted block first along the left vertical wall (Case-I) and then along the right vertical wall (Case-II) to test the maximum heat transfer effects. The changes in main characteristics of the flow due to variation of Reynolds number and Rayleigh number are elaborated. The effect of various flow parameters on the thermal conductivity behavior for both cases is discussed based on average Nusselt number and bulk-average temperature and found that Case-I shows higher heat transfer rate compared to Case-II, for higher Re, Ra and ϕϕ.

  Abstract
  This work is focussed on the numerical modeling of mixed convection heat transfer effects in a lid-driven cavity filled with a copper–water nanofluid. A heated wall mounted [...]

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• Heat transfer analysis of boundary layer flow over hyperbolic stretching cylinder

  A. Majeed, T. Javed, I. Mustafa

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In the present study heat transfer and entropy generation analysis of boundary layer flow of an incompressible viscous fluid over hyperbolic stretching cylinder are taken into account. The governing nonlinear partial differential equations are normalized by using suitable transformations. The numerical results are obtained for the partial differential equations by a finite difference scheme known as Keller box method. The influence of emerging parameters namely curvature parameter and Prandtl number on velocity and temperature profiles, skin friction coefficient and the Nusselt number is presented through graphs. A comparison for the flat plate case is given and developed code is validated. It is seen that curvature parameter has dominant effect on the flow and heat transfer characteristics. The increment in the curvature of the hyperbolic stretching cylinder increases both the momentum and thermal boundary layers. Also skin friction coefficient at the surface of cylinder decreases but Nusselt number shows opposite results. Temperature distribution is decreasing by increasing Prandtl number. Moreover, the effects of different physical parameters on entropy generation number and Bejan number are shown graphically.

  Abstract
  In the present study heat transfer and entropy generation analysis of boundary layer flow of an incompressible viscous fluid over hyperbolic stretching cylinder are taken [...]

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• Adsorption of rhodamine B and methylene blue dyes using waste of seeds of Aleurites Moluccana, a low cost adsorbent

  D. Postai, C. Demarchi, F. Zanatta, D. Melo, C. Rodrigues

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds Aleurites moluccana (WAM) was studied in a batch system. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), point of zero charge measurement, and the Boehm titration method. The effects of contact time and pH were investigated for the removal of cationic dyes. An increase in pH from 3 to 9 was accompanied by an approximately three-fold increase in the amount of dye adsorbed. The adsorptions equilibrium values were obtained and analyzed using the Langmuir, Freundlich, Sips, and Redlich–Peterson equations, the Sips isotherm being the one that showed the best correlation with the experimental values. The maximum adsorption capacities of the dyes were 178 mg/g for the MB and 117 mg/g for the RhB. The kinetic sorption was evaluated by the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, where it was observed that sorption follows the pseudo-second-order kinetic model. The study of thermodynamics showed that the adsorption is a spontaneous and endothermic process. The results indicate that waste seeds of A. moluccana could be used as a low cost material for the removal of cationic dyes from wastewater.

  Abstract
  Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds Aleurites moluccana (WAM) was studied in a batch system. The adsorbent was characterized [...]

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• Soft sensing of product quality in the debutanizer column with principal component analysis and feed-forward artificial neural network

  A. Pani, K. Amin, H. Mohanta

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  In this work, data-driven soft sensors are developed for the debutanizer column for online monitoring of butane content in the debutanizer column bottom product. The data set consists of data for seven process inputs and one process output. The total process data were equally divided into a training set and a validation set using the Kennard–Stone maximal intra distance criterion. The training set was used to develop multiple linear regression, principal component regression and back propagation neural network models for the debutanizer column. Performances of the developed models were assessed by simulation with the validation data set. Results show that the neural network model designed using Levenberg–Marquardt algorithm is capable of estimating the product quality with nearly 95% accuracy. The performance of the neural network model reported in this article is found to be better than the performances of least square support vector regression and standard support vector regression models reported in the literature earlier.

  Abstract
  In this work, data-driven soft sensors are developed for the debutanizer column for online monitoring of butane content in the debutanizer column bottom product. The data [...]

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• Nonlinear peristaltic motion of a Johnson–Segalman fluid in a tapered asymmetric channel

  M. Kothandapani, J. Prakash, V. Pushparaj

  Collection of Alexandria Engineering Journal (2017).

  
  

  Abstract

  The peristaltic flow analysis in a tapered asymmetric channel has been made for a Johnson–Segalman fluid. The tapered asymmetric channel is assumed to be formed due to a peristaltic wave train on the non-uniform walls having different amplitudes and phase. Two-dimensional equations of a Johnson–Segalman fluid have been simplified by treating a long wavelength and low Reynolds number approximations. The reduced equations are then solved for the stream function, axial velocity and axial pressure gradient using a regular perturbation technique. The expressions for the pressure rise, axial velocity and stream function are sketched and the reasons for the variations observed in various physical parameters are interpreted with valid theory. It has been noticed that peristaltic pumping region and free pumping decrease with an increase in non-uniform parameter and the situation is quite complimentary to the case of augmented pumping. It has also been observed that the size of the tapped bolus decreases with an increase in Weissenberg number.

  Abstract
  The peristaltic flow analysis in a tapered asymmetric channel has been made for a Johnson–Segalman fluid. The tapered asymmetric channel is assumed to be formed due to a [...]

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