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Volume 27 (2022): Issue 4 (December 2022)

Volume 27 (2022): Issue 3 (September 2022)

Volume 27 (2022): Issue 2 (June 2022)

Volume 27 (2022): Issue 1 (March 2022)

Volume 26 (2021): Issue 4 (December 2021)

Volume 26 (2021): Issue 3 (September 2021)

Volume 26 (2021): Issue 2 (June 2021)

Volume 26 (2021): Issue 1 (March 2021)

Volume 25 (2020): Issue 4 (December 2020)

Volume 25 (2020): Issue 3 (September 2020)

Volume 25 (2020): Issue 2 (June 2020)

Volume 25 (2020): Issue 1 (March 2020)

Volume 24 (2019): Issue 4 (December 2019)

Volume 24 (2019): Issue 3 (September 2019)

Volume 24 (2019): Issue 2 (June 2019)

Volume 24 (2019): Issue 1 (March 2019)

Volume 23 (2018): Issue 4 (November 2018)

Volume 23 (2018): Issue 3 (August 2018)

Volume 23 (2018): Issue 2 (May 2018)

Volume 23 (2018): Issue 1 (February 2018)

Volume 22 (2017): Issue 4 (December 2017)

Volume 22 (2017): Issue 3 (August 2017)

Volume 22 (2017): Issue 2 (May 2017)

Volume 22 (2017): Issue 1 (February 2017)

Volume 21 (2016): Issue 4 (December 2016)

Volume 21 (2016): Issue 3 (August 2016)

Volume 21 (2016): Issue 2 (May 2016)

Volume 21 (2016): Issue 1 (February 2016)

Volume 20 (2015): Issue 4 (December 2015)

Volume 20 (2015): Issue 3 (August 2015)

Volume 20 (2015): Issue 2 (May 2015)

Volume 20 (2015): Issue 1 (February 2015)

Volume 19 (2014): Issue 4 (December 2014)

Volume 19 (2014): Issue 3 (August 2014)

Volume 19 (2014): Issue 2 (May 2014)

Volume 19 (2014): Issue 1 (February 2014)

Volume 18 (2013): Issue 4 (December 2013)

Volume 18 (2013): Issue 3 (August 2013)

Volume 18 (2013): Issue 2 (June 2013)

Volume 18 (2013): Issue 1 (March 2013)

Journal Details
Format
Journal
eISSN
2353-9003
ISSN
1734-4492
First Published
19 Apr 2013
Publication timeframe
4 times per year
Languages
English

Search

Volume 24 (2019): Issue 4 (December 2019)

Journal Details
Format
Journal
eISSN
2353-9003
ISSN
1734-4492
First Published
19 Apr 2013
Publication timeframe
4 times per year
Languages
English

Search

15 Articles
Open Access

Triple Diffusive Convection of a Non-Newtonian Fluid Under the Combined Effect of Compressibility and Variable Gravity

Published Online: 04 Dec 2019
Page range: 1 - 11

Abstract

Abstract

In this paper, triple diffusive convection in a Rivlin-Ericksen fluid layer, which is permeated with suspended particles in the porous medium under the effect of compressibility and variable gravity, is investigated. Linear stability theory and normal mode analysis have been used to study the problem under consideration. It is observed that, for stationary convection, suspended particles, compressibility and medium permeability have destabilizing/stabilizing effects under certain conditions. The variable gravity parameter destabilizes the system whereas stable solute gradients have a stabilizing effect.

Keywords

  • triple diffusion
  • Rivlin-Ericksen fluid
  • suspended particles
  • porous medium
  • compressibility
  • variable gravity
Open Access

Effects of Viscous Dissipation and Wall Conduction on Steady Mixed Convection Couette Flow of Heat Generating/Absorbing Fluid

Published Online: 04 Dec 2019
Page range: 12 - 35

Abstract

Abstract

This article theoretically investigated mixed convection flow of heat generating/absorbing fluid in the presence of viscous dissipation and wall conduction effects. The flow is considered to be steady in a vertical channel with some boundary thickness. One of the plates is heated while the other is kept at ambient temperature. The governing flow equations were solved analytically using Homotopy Perturbation Method (HPM). The influences of the governing parameters were captured in graphs, tables and a table was constructed for validation of the work. It is worthwhile to stress that, both the velocity and temperature profiles decrease near the heated plate with an increase in boundary thickness (d) while the reverse cases were observed toward the cold plate. The velocity profile increases near the heated plate with increase in mixed convection parameter (Gre) and decreases towards the cold plate. Rate of heat transfer has been observed to decrease with increase in boundary plate thickness (d) while the critical value of (Gre) increases with growing boundary plate thickness. The study therefore established the importance of boundary plate thickness in mixed convection investigation.

Keywords

  • mixed convection
  • viscous dissipation
  • vertical channel
  • boundary thickness
  • mass constant flux
Open Access

Effects of Non-Uniform Heat Generation/Absorption and Radiation on Hydromagnetic Dissipative Flow over a Porous Nonlinear Stretching Surface with Heat and Mass Fluxes

Published Online: 04 Dec 2019
Page range: 36 - 52

Abstract

Abstract

Forced convective heat and mass transfer flow of hydromagnetic, radiating and dissipative fluid over a porous nonlinear stretching sheet in the presence of non-uniform heat generation/absorption is investigated numerically. The system of nonlinear partial differential equations governing the physical problem is reduced to nonlinear ordinary differential equations by means of suitable similarity transformations and are solved numerically using Nachtsheim Swigert shooting iteration scheme together with fourth order Runge Kutta method. The effects of various physical parameters on velocity, temperature and concentration distributions are depicted graphically. The important findings of this study exhibited that the effect of non-uniform heat generation/absorption parameter and radiation parameter have significant role in controlling thermal boundary layer thickness and temperature. Numerical values of the skin friction coefficient, temperature and concentration at the wall are shown in a tabular form. A comparison is made with previously published data which results in good agreement.

Keywords

  • MHD
  • heat flux
  • mass flux
  • non-uniform heat generation/absorption
Open Access

Investigation of Waves Generated in Transversely Isotropic Micropolar Generalized Thermoelastic Half Space Under Temperature Dependent Properties

Published Online: 04 Dec 2019
Page range: 53 - 65

Abstract

Abstract

The present study deals with the propagation of waves in a transversely isotropic micropolar generalized thermoelastic material possessing temperature dependent elastic properties. After developing the solution for LS, GL and CT theory, the phase velocities and attenuation quality factor have been obtained. The expressions for amplitudes of stresses, displacements, microratation and temperature distribution have been derived and computed numerically. The numerically evaluated results have been plotted graphically. Some particular cases of interest have also been obtained.

Keywords

  • micropolar
  • transversely isotropic
  • generalized thermoelastic
  • amplitude ratios
Open Access

Mass Transport Through Interstitial Structures

Published Online: 04 Dec 2019
Page range: 66 - 91

Abstract

Abstract

Interstitial space, also called interstitum, separating the vital organs of a human body, is the primary source of lymph and is a major fluid compartment in the body.

Interstitial space (IS) is filled out by thick collagen (CL) bundles which form lattices represented by a network of capillaries. This network has the structure similar to a sponge porous matrix (SPM) with pores-capillaries of variable cross-section.

To analyse the mass transport of interstitial fluids (IFs) through the porous matrix it is assumed that the SPM is composed of an irregular system of pores which may be modelled as a fractal porous matrix. The interstitial fluids can be either bio-suspensions or bio-solutions and therefore they have to be modelled as non-Newtonian fluids. Analysing the fluid flow through the porous matrix it is assumed that the SPM is modelled as capillary tubes of variable radii. Introducing a hindrance factor allowed us to consider the porous matrix as a system of fractal capillaries but of constant radii.

Classical and fractal expressions for the flow rate, velocity and permeability are derived based on the physical properties of the capillary model of interstitial structures. Each parameter in the proposed expressions does not contain any empirical constant and has a clear physical meaning, and the proposed fractals models relate the flow properties of the fluids under consideration with the structural parameters of interstitium as a porous medium.

Keywords

  • interstitial space
  • interstitial fluids
  • fractal models
Open Access

Role of Sudden Application or Withdrawal of Magnetic Field on MHD Couette Flow

Published Online: 04 Dec 2019
Page range: 92 - 105

Abstract

Abstract

This article investigates the impact of a sudden application or sudden withdrawal of a magnetic field on an unsteady MHD Couette flow formation in a parallel plate channel. The governing momentum equation is derived and solved exactly in Laplace domain using the Laplace transform technique with the necessary initial and boundary conditions to capture the present physical situation for the cases; sudden application or sudden withdrawal of a magnetic field. Due to the complexity of the solution obtained, the Riemann-sum approximation technique is used to transform the Laplace domain to time domain. During the course of graphical and tabular representations, results show that the Hartmann number, time and nature of application of a magnetic field play an important role in the transition from hydrodynamic to magnetohydrodynamic flow and vice-versa. Also, fluid velocity steady-state solution is independent on whether the magnetic field is fixed relative to the moving plate or to the fluid for sudden withdrawal of magnetic field. In addition, the application of a sudden magnetic field leads to a delay in the attainment of steady-state solution.

Keywords

  • MHD
  • Couette motion
  • Riemann-sum approximation
  • Hartmann number
  • parallel plates
Open Access

Electro-Hydrodynamic Convection in a Rotating Dielectric Micropolar Fluid Layer

Published Online: 04 Dec 2019
Page range: 106 - 124

Abstract

Abstract

Thermal convection of a rotating dielectric micropolar fluid layer under the action of an electric field and temperature gradient has been investigated. The dispersion relation has been derived using normal mode analysis. The effects of the electric Rayleigh number, micropolar viscosity, Taylor number and Prandtl number on stability and over stability criteria are discussed. It is found that rotation postpones the instability in the fluid layer, while the Prandtl number and rotation both have a stabilizing effect. It is also observed that the micropolar fluid additives have a stabilizing effect, whereas the electric field has a destabilizing effect on the onset of convection stability.

Keywords

  • convection
  • rotation
  • electric
  • Rayleigh number
  • Taylor number
  • normal-mode
Open Access

The Impact of Radiation Effect on MHD Stagnation-Point Flow of a Nanofluid over an Exponentially Stretching Sheet in the Presence of Chemical Reaction

Published Online: 04 Dec 2019
Page range: 125 - 139

Abstract

Abstract

The present study is to investigate the effect of the chemical reaction parameter on stagnation point flow of magnetohydrodynamics field past an exponentially stretching sheet by considering a nanofluid. The problem is governed by governing coupled nonlinear partial differential equations with appropriate boundary conditions. The transformed non-dimensional and coupled governing ordinary differential equations are solved numerically using the fourth order Adams-Bashforth Moulton method. The effects of various dimensionless parameters on velocity, temperature and concentration fields are studied and then the results are presented in both tabular and graphical forms.

Keywords

  • numerical solution
  • MHD
  • radiation effect
  • stagnation-point flow
  • chemical reaction
  • nanofluid
Open Access

Identification of Local Elastic Parameters in Heterogeneous Materials Using a Parallelized Femu Method

Published Online: 04 Dec 2019
Page range: 140 - 156

Abstract

Abstract

In this work, we explore the possibilities of the widespread Finite Element Model Updating method (FEMU) in order to identify the local elastic mechanical properties in heterogeneous materials. The objective function is defined as a quadratic error of the discrepancy between measured fields and simulated ones. We compare two different formulations of the function, one based on the displacement fields and one based on the strain fields. We use a genetic algorithm in order to minimize these functions. We prove that the strain functional associated with the genetic algorithm is the best combination. We then improve the implementation of the method by parallelizing the algorithm in order to reduce the computation cost. We validate the approach with simulated cases in 2D.

Keywords

  • identification
  • elasticity
  • heterogeneous material
  • genetic algorithm
  • parallel computation
Open Access

Water Wave Scattering by an Infinite Step in the Presence of an Ice-Cover

Published Online: 04 Dec 2019
Page range: 157 - 168

Abstract

Abstract

The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finite and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absence of ice-cover, the results for the free surface are recovered.

Keywords

  • water wave scattering
  • ice-cover
  • infinite step
  • integral equation
  • Galerkin approximation
  • reflection and transmission coefficients
Open Access

Effects of Chemical Reaction on Transient MHD Flow with Mass Transfer Past an Impulsively Fixed Infinite Vertical Plate in the Presence of Thermal Radiation

Published Online: 04 Dec 2019
Page range: 169 - 182

Abstract

Abstract

The effects of chemical reaction on a transient MHD mixed convection flow with mass transfer past an impulsively fixed infinite vertical plate under the influence of a transverse magnetic field have been presented. The medium is considered to be non-scattering and the fluid to be non-gray having emitting-absorbing and optically thick radiation limit properties. The dimensionless governing equations of the flow and mass transfer with boundary conditions are solved numerically by using the Ritz finite element method. The numerical results for the velocity, temperature and the concentration profiles as well as the skin-friction coefficient for different values of physical parameters such as the radiation parameter, magnetic parameter, Schmidt number and chemical reaction parameter have been obtained and presented through graphs and tables. It has been found that there is a fall in the temperature and velocity for both air and water as the radiation parameter is increased. An increase in the Schmidt number and chemical reaction parameter results a decrease in the concentration and velocity profiles for both air and water. Furthermore, an increase in the radiation parameter, magnetic parameter, Schmidt number and chemical reaction parameter decreases the skin-friction.

Keywords

  • MHD
  • magnetic field
  • fixed vertical plate
  • chemical reaction parameter
  • radiation parameter
Open Access

Nanofluid Motion Past a Shrinking Sheet in Porous Media Under the Impact of Radiation and Heat Source/Sink

Published Online: 04 Dec 2019
Page range: 183 - 199

Abstract

Abstract

An investigation has been carried out for the MHD 3-dimensional flow of nanofluid over a shrinking sheet saturating a porous media in the presence of thermal radiation and heat generation. Convective boundary conditions for the flow phenomena are used in the present analysis. The governing equations are reduced to ODEs employing suitable similarity transformations. The solutions of formulated differential equations have been attained mathematically by fourth order R-K technique along with the shooting method. The impact of the governing constraints on momentum, heat, and local Nusselt number, are explored. It is noticed that the momentum and heat decrease with raise in the porosity variable, temperature reduces with an enhance in the thermal radiation variable, and temperature enhances with an enhance in the heat source/sink parameter.

Keywords

  • MHD
  • nanofluid
  • shrinking surface
  • thermal radiation
  • heat generation
  • porous medium
  • convective conditions
Open Access

Application of Two Conditions of Loss of Stability in Analysis of the Tube Bending Process

Published Online: 04 Dec 2019
Page range: 200 - 223

Abstract

Abstract

In this paper, the derivation of expressions for admissible values of strains and stresses for vertex points of layers subjected to tension during tube bending at bending machines is presented. The conditions of the dispersed and located loss of stability of the bent tube were assumed as criteria of instability. The original element of this paper is the extension of the criterion of strain location in a form of possible initiation of a neck or furrow (introduced by Marciniak for thin plates [1]) to bending thin- and thick-walled metal tubes at bending machines. The conditions of the dispersed and localized loss of stability together with formation of the plane state of deformation (PSD) in the plane stress state (PSS) were assumed as the criteria of instability. The calculation results were presented as graphs being useful nomograms. We present also simple examples of calculations of permissible and critical strains and values of bending angles including and not including displacement of the neutral axis y0, during cold bending metal thin-walled tubes at bending machines for bending angles <0o; 180o>.

Keywords

  • allowable strains and stresses
  • bending angles
  • neutral layer
  • wall thickness of elbows
Open Access

On the Fractography and Some Strength Properties of Fe-Based Sintered Materials with Multicomponent Oxide Microadditives

Published Online: 04 Dec 2019
Page range: 224 - 229

Abstract

Abstract

In the present paper, the effect of alumina and zirconia microadditives on the compressive strength and flexural strength of sintered Fe-based powder materials is shown. It was found that intercrystalline fractures, both plastic and brittle, are observed when bending. During compression, fractures are observed too, as well as flaking of thin near-surface layers. The intensity of such flaking depends on the composition of the sintered material. Strength parameters of the materials studied also depend on additives composition and quantity. The lowest parameters are observed for a material that contains 1% alumina particulates. The compressive strength of a material containing zirconia particulates increases 3 times and the flexural strength 2 times.

Keywords

  • Fe-based sintered materials
  • oxide additives
  • fracture analyze
  • flexural strength
  • compressive strength
Open Access

Motion Analysis of the Hydraulic Ladder

Published Online: 04 Dec 2019
Page range: 230 - 240

Abstract

Abstract

This paper is aimed at a dynamic analysis of a hydraulically lifted ladder by means of analytical and numerical calculations. The solutions used in the dynamic analysis of mechanical systems were used in the analytical solution. A numerical model was created to verify the achieved results of the solved mechanical system with simulation of its motion.

Keywords

  • motion
  • hydraulic lifting ladder
  • velocity
  • acceleration
15 Articles
Open Access

Triple Diffusive Convection of a Non-Newtonian Fluid Under the Combined Effect of Compressibility and Variable Gravity

Published Online: 04 Dec 2019
Page range: 1 - 11

Abstract

Abstract

In this paper, triple diffusive convection in a Rivlin-Ericksen fluid layer, which is permeated with suspended particles in the porous medium under the effect of compressibility and variable gravity, is investigated. Linear stability theory and normal mode analysis have been used to study the problem under consideration. It is observed that, for stationary convection, suspended particles, compressibility and medium permeability have destabilizing/stabilizing effects under certain conditions. The variable gravity parameter destabilizes the system whereas stable solute gradients have a stabilizing effect.

Keywords

  • triple diffusion
  • Rivlin-Ericksen fluid
  • suspended particles
  • porous medium
  • compressibility
  • variable gravity
Open Access

Effects of Viscous Dissipation and Wall Conduction on Steady Mixed Convection Couette Flow of Heat Generating/Absorbing Fluid

Published Online: 04 Dec 2019
Page range: 12 - 35

Abstract

Abstract

This article theoretically investigated mixed convection flow of heat generating/absorbing fluid in the presence of viscous dissipation and wall conduction effects. The flow is considered to be steady in a vertical channel with some boundary thickness. One of the plates is heated while the other is kept at ambient temperature. The governing flow equations were solved analytically using Homotopy Perturbation Method (HPM). The influences of the governing parameters were captured in graphs, tables and a table was constructed for validation of the work. It is worthwhile to stress that, both the velocity and temperature profiles decrease near the heated plate with an increase in boundary thickness (d) while the reverse cases were observed toward the cold plate. The velocity profile increases near the heated plate with increase in mixed convection parameter (Gre) and decreases towards the cold plate. Rate of heat transfer has been observed to decrease with increase in boundary plate thickness (d) while the critical value of (Gre) increases with growing boundary plate thickness. The study therefore established the importance of boundary plate thickness in mixed convection investigation.

Keywords

  • mixed convection
  • viscous dissipation
  • vertical channel
  • boundary thickness
  • mass constant flux
Open Access

Effects of Non-Uniform Heat Generation/Absorption and Radiation on Hydromagnetic Dissipative Flow over a Porous Nonlinear Stretching Surface with Heat and Mass Fluxes

Published Online: 04 Dec 2019
Page range: 36 - 52

Abstract

Abstract

Forced convective heat and mass transfer flow of hydromagnetic, radiating and dissipative fluid over a porous nonlinear stretching sheet in the presence of non-uniform heat generation/absorption is investigated numerically. The system of nonlinear partial differential equations governing the physical problem is reduced to nonlinear ordinary differential equations by means of suitable similarity transformations and are solved numerically using Nachtsheim Swigert shooting iteration scheme together with fourth order Runge Kutta method. The effects of various physical parameters on velocity, temperature and concentration distributions are depicted graphically. The important findings of this study exhibited that the effect of non-uniform heat generation/absorption parameter and radiation parameter have significant role in controlling thermal boundary layer thickness and temperature. Numerical values of the skin friction coefficient, temperature and concentration at the wall are shown in a tabular form. A comparison is made with previously published data which results in good agreement.

Keywords

  • MHD
  • heat flux
  • mass flux
  • non-uniform heat generation/absorption
Open Access

Investigation of Waves Generated in Transversely Isotropic Micropolar Generalized Thermoelastic Half Space Under Temperature Dependent Properties

Published Online: 04 Dec 2019
Page range: 53 - 65

Abstract

Abstract

The present study deals with the propagation of waves in a transversely isotropic micropolar generalized thermoelastic material possessing temperature dependent elastic properties. After developing the solution for LS, GL and CT theory, the phase velocities and attenuation quality factor have been obtained. The expressions for amplitudes of stresses, displacements, microratation and temperature distribution have been derived and computed numerically. The numerically evaluated results have been plotted graphically. Some particular cases of interest have also been obtained.

Keywords

  • micropolar
  • transversely isotropic
  • generalized thermoelastic
  • amplitude ratios
Open Access

Mass Transport Through Interstitial Structures

Published Online: 04 Dec 2019
Page range: 66 - 91

Abstract

Abstract

Interstitial space, also called interstitum, separating the vital organs of a human body, is the primary source of lymph and is a major fluid compartment in the body.

Interstitial space (IS) is filled out by thick collagen (CL) bundles which form lattices represented by a network of capillaries. This network has the structure similar to a sponge porous matrix (SPM) with pores-capillaries of variable cross-section.

To analyse the mass transport of interstitial fluids (IFs) through the porous matrix it is assumed that the SPM is composed of an irregular system of pores which may be modelled as a fractal porous matrix. The interstitial fluids can be either bio-suspensions or bio-solutions and therefore they have to be modelled as non-Newtonian fluids. Analysing the fluid flow through the porous matrix it is assumed that the SPM is modelled as capillary tubes of variable radii. Introducing a hindrance factor allowed us to consider the porous matrix as a system of fractal capillaries but of constant radii.

Classical and fractal expressions for the flow rate, velocity and permeability are derived based on the physical properties of the capillary model of interstitial structures. Each parameter in the proposed expressions does not contain any empirical constant and has a clear physical meaning, and the proposed fractals models relate the flow properties of the fluids under consideration with the structural parameters of interstitium as a porous medium.

Keywords

  • interstitial space
  • interstitial fluids
  • fractal models
Open Access

Role of Sudden Application or Withdrawal of Magnetic Field on MHD Couette Flow

Published Online: 04 Dec 2019
Page range: 92 - 105

Abstract

Abstract

This article investigates the impact of a sudden application or sudden withdrawal of a magnetic field on an unsteady MHD Couette flow formation in a parallel plate channel. The governing momentum equation is derived and solved exactly in Laplace domain using the Laplace transform technique with the necessary initial and boundary conditions to capture the present physical situation for the cases; sudden application or sudden withdrawal of a magnetic field. Due to the complexity of the solution obtained, the Riemann-sum approximation technique is used to transform the Laplace domain to time domain. During the course of graphical and tabular representations, results show that the Hartmann number, time and nature of application of a magnetic field play an important role in the transition from hydrodynamic to magnetohydrodynamic flow and vice-versa. Also, fluid velocity steady-state solution is independent on whether the magnetic field is fixed relative to the moving plate or to the fluid for sudden withdrawal of magnetic field. In addition, the application of a sudden magnetic field leads to a delay in the attainment of steady-state solution.

Keywords

  • MHD
  • Couette motion
  • Riemann-sum approximation
  • Hartmann number
  • parallel plates
Open Access

Electro-Hydrodynamic Convection in a Rotating Dielectric Micropolar Fluid Layer

Published Online: 04 Dec 2019
Page range: 106 - 124

Abstract

Abstract

Thermal convection of a rotating dielectric micropolar fluid layer under the action of an electric field and temperature gradient has been investigated. The dispersion relation has been derived using normal mode analysis. The effects of the electric Rayleigh number, micropolar viscosity, Taylor number and Prandtl number on stability and over stability criteria are discussed. It is found that rotation postpones the instability in the fluid layer, while the Prandtl number and rotation both have a stabilizing effect. It is also observed that the micropolar fluid additives have a stabilizing effect, whereas the electric field has a destabilizing effect on the onset of convection stability.

Keywords

  • convection
  • rotation
  • electric
  • Rayleigh number
  • Taylor number
  • normal-mode
Open Access

The Impact of Radiation Effect on MHD Stagnation-Point Flow of a Nanofluid over an Exponentially Stretching Sheet in the Presence of Chemical Reaction

Published Online: 04 Dec 2019
Page range: 125 - 139

Abstract

Abstract

The present study is to investigate the effect of the chemical reaction parameter on stagnation point flow of magnetohydrodynamics field past an exponentially stretching sheet by considering a nanofluid. The problem is governed by governing coupled nonlinear partial differential equations with appropriate boundary conditions. The transformed non-dimensional and coupled governing ordinary differential equations are solved numerically using the fourth order Adams-Bashforth Moulton method. The effects of various dimensionless parameters on velocity, temperature and concentration fields are studied and then the results are presented in both tabular and graphical forms.

Keywords

  • numerical solution
  • MHD
  • radiation effect
  • stagnation-point flow
  • chemical reaction
  • nanofluid
Open Access

Identification of Local Elastic Parameters in Heterogeneous Materials Using a Parallelized Femu Method

Published Online: 04 Dec 2019
Page range: 140 - 156

Abstract

Abstract

In this work, we explore the possibilities of the widespread Finite Element Model Updating method (FEMU) in order to identify the local elastic mechanical properties in heterogeneous materials. The objective function is defined as a quadratic error of the discrepancy between measured fields and simulated ones. We compare two different formulations of the function, one based on the displacement fields and one based on the strain fields. We use a genetic algorithm in order to minimize these functions. We prove that the strain functional associated with the genetic algorithm is the best combination. We then improve the implementation of the method by parallelizing the algorithm in order to reduce the computation cost. We validate the approach with simulated cases in 2D.

Keywords

  • identification
  • elasticity
  • heterogeneous material
  • genetic algorithm
  • parallel computation
Open Access

Water Wave Scattering by an Infinite Step in the Presence of an Ice-Cover

Published Online: 04 Dec 2019
Page range: 157 - 168

Abstract

Abstract

The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finite and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absence of ice-cover, the results for the free surface are recovered.

Keywords

  • water wave scattering
  • ice-cover
  • infinite step
  • integral equation
  • Galerkin approximation
  • reflection and transmission coefficients
Open Access

Effects of Chemical Reaction on Transient MHD Flow with Mass Transfer Past an Impulsively Fixed Infinite Vertical Plate in the Presence of Thermal Radiation

Published Online: 04 Dec 2019
Page range: 169 - 182

Abstract

Abstract

The effects of chemical reaction on a transient MHD mixed convection flow with mass transfer past an impulsively fixed infinite vertical plate under the influence of a transverse magnetic field have been presented. The medium is considered to be non-scattering and the fluid to be non-gray having emitting-absorbing and optically thick radiation limit properties. The dimensionless governing equations of the flow and mass transfer with boundary conditions are solved numerically by using the Ritz finite element method. The numerical results for the velocity, temperature and the concentration profiles as well as the skin-friction coefficient for different values of physical parameters such as the radiation parameter, magnetic parameter, Schmidt number and chemical reaction parameter have been obtained and presented through graphs and tables. It has been found that there is a fall in the temperature and velocity for both air and water as the radiation parameter is increased. An increase in the Schmidt number and chemical reaction parameter results a decrease in the concentration and velocity profiles for both air and water. Furthermore, an increase in the radiation parameter, magnetic parameter, Schmidt number and chemical reaction parameter decreases the skin-friction.

Keywords

  • MHD
  • magnetic field
  • fixed vertical plate
  • chemical reaction parameter
  • radiation parameter
Open Access

Nanofluid Motion Past a Shrinking Sheet in Porous Media Under the Impact of Radiation and Heat Source/Sink

Published Online: 04 Dec 2019
Page range: 183 - 199

Abstract

Abstract

An investigation has been carried out for the MHD 3-dimensional flow of nanofluid over a shrinking sheet saturating a porous media in the presence of thermal radiation and heat generation. Convective boundary conditions for the flow phenomena are used in the present analysis. The governing equations are reduced to ODEs employing suitable similarity transformations. The solutions of formulated differential equations have been attained mathematically by fourth order R-K technique along with the shooting method. The impact of the governing constraints on momentum, heat, and local Nusselt number, are explored. It is noticed that the momentum and heat decrease with raise in the porosity variable, temperature reduces with an enhance in the thermal radiation variable, and temperature enhances with an enhance in the heat source/sink parameter.

Keywords

  • MHD
  • nanofluid
  • shrinking surface
  • thermal radiation
  • heat generation
  • porous medium
  • convective conditions
Open Access

Application of Two Conditions of Loss of Stability in Analysis of the Tube Bending Process

Published Online: 04 Dec 2019
Page range: 200 - 223

Abstract

Abstract

In this paper, the derivation of expressions for admissible values of strains and stresses for vertex points of layers subjected to tension during tube bending at bending machines is presented. The conditions of the dispersed and located loss of stability of the bent tube were assumed as criteria of instability. The original element of this paper is the extension of the criterion of strain location in a form of possible initiation of a neck or furrow (introduced by Marciniak for thin plates [1]) to bending thin- and thick-walled metal tubes at bending machines. The conditions of the dispersed and localized loss of stability together with formation of the plane state of deformation (PSD) in the plane stress state (PSS) were assumed as the criteria of instability. The calculation results were presented as graphs being useful nomograms. We present also simple examples of calculations of permissible and critical strains and values of bending angles including and not including displacement of the neutral axis y0, during cold bending metal thin-walled tubes at bending machines for bending angles <0o; 180o>.

Keywords

  • allowable strains and stresses
  • bending angles
  • neutral layer
  • wall thickness of elbows
Open Access

On the Fractography and Some Strength Properties of Fe-Based Sintered Materials with Multicomponent Oxide Microadditives

Published Online: 04 Dec 2019
Page range: 224 - 229

Abstract

Abstract

In the present paper, the effect of alumina and zirconia microadditives on the compressive strength and flexural strength of sintered Fe-based powder materials is shown. It was found that intercrystalline fractures, both plastic and brittle, are observed when bending. During compression, fractures are observed too, as well as flaking of thin near-surface layers. The intensity of such flaking depends on the composition of the sintered material. Strength parameters of the materials studied also depend on additives composition and quantity. The lowest parameters are observed for a material that contains 1% alumina particulates. The compressive strength of a material containing zirconia particulates increases 3 times and the flexural strength 2 times.

Keywords

  • Fe-based sintered materials
  • oxide additives
  • fracture analyze
  • flexural strength
  • compressive strength
Open Access

Motion Analysis of the Hydraulic Ladder

Published Online: 04 Dec 2019
Page range: 230 - 240

Abstract

Abstract

This paper is aimed at a dynamic analysis of a hydraulically lifted ladder by means of analytical and numerical calculations. The solutions used in the dynamic analysis of mechanical systems were used in the analytical solution. A numerical model was created to verify the achieved results of the solved mechanical system with simulation of its motion.

Keywords

  • motion
  • hydraulic lifting ladder
  • velocity
  • acceleration

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