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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 18 (2013): Issue 4 (December 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

19 Articles
Open Access

Closed form solutions of heat and mass transfer in the flow of a MHD visco-elastic fluid over a porous stretching sheet

Published Online: 07 Mar 2014
Page range: 989 - 1002

Abstract

Abstract

The problem of heat and mass transfer in a visco-elastic fluid flow over a stretching sheet in the presence of a uniform magnetic field is examined. The important physical quantities such as the skin friction coefficient, heat transfer co-efficient and the mass transfer co-efficient are determined. It is found that the heat and mass transfer distribution decreases with the increasing values of the visco-elastic parameter k1.

Keywords

  • heat and mass transfer
  • MHD flow
  • porous stretching sheet
  • visco-elastic fluid
Open Access

Boundary layer flow and heat transfer over a permeable shrinking cylinder with surface mass transfer

Published Online: 07 Mar 2014
Page range: 1003 - 1012

Abstract

Abstract

In the present paper, the axisymmetric boundary layer flow and heat transfer past a permeable shrinking cylinder subject to surface mass transfer is studied. The similarity transformations are adopted to convert the governing partial differential equations for the flow and heat transfer into the nonlinear self-similar ordinary differential equations and then solved by a finite difference method using the quasilinearization technique. From the current investigation, it is found that the velocity in the boundary layer region decreases with the curvature parameter and increases with suction mass transfer. Moreover, with the increase of the curvature parameter, the suction parameter and Prandtl number, the heat transfer is enhanced.

Keywords

  • boundary layer
  • heat transfer
  • shrinking cylinder
  • mass suction
Open Access

Wave propagation in micropolar monoclinic thermoelastic half space

Published Online: 07 Mar 2014
Page range: 1013 - 1023

Abstract

Abstract

Propagation of waves in a micropolar monoclinic medium possessing hermoelastic properties based on the Lord- Shulman (L-S),Green and Lindsay (G-L) and Coupled thermoelasticty (C-T) theories is discussed. The investigation is divided into two sections, viz., plane strain and anti-plane strain problem. After developing the solution, the phase velocities and attenuation quality factor have been derived and computed numerically. The numerical results have been plotted graphically.

Keywords

  • micropolar
  • monoclinic
  • generalized thermoelastic
Open Access

Three-dimensional oscillating flow between two parallel plates through a porous medium

Published Online: 07 Mar 2014
Page range: 1025 - 1037

Abstract

Abstract

An unsteady Couette flow between two parallel plates when upper plates oscillates in its own plane and is subjected to a constant suction and the lower plate to a injection velocity distribution through the porous medium has been analyzed. The approximate solution has been obtained using perturbation technique. It is seen that the primary velocity increases whereas the secondary velocity decreases with an increase in permeability parameter. It is also found that the primary velocity increases with an increase in the Reynolds number as well as the suction parameter. The magnitude of the secondary velocity increases near the stationary plate but decreases near the oscillating plate with an increase in the Reynolds number. Whereas, it increases with an increase in the suction parameter.

Keywords

  • Couette flow
  • three-dimensional
  • injection
  • suction
  • transverse sinusoidal
Open Access

Unsteady hydromagnetic couette flow due to ramped motion of one of the porous plates

Published Online: 07 Mar 2014
Page range: 1039 - 1056

Abstract

Abstract

An unsteady flow formation in Couette motion of an electrically conducting fluid subject to transverse magnetic field has been analyzed in the presence of suction/injection through the porous plates when one of the porous plates is in ramped motion. It is assumed that the porous plates are uniformly permeable and the fluid is entering the flow region through one of the porous plates at same rate as it is leaving through the other porous plate. The resulting boundary value problem has been solved exactly under the assumption of a negligible induced magnetic field, external electric field and pressure gradient. Unified closed form expressions for the velocity field and skin-friction corresponding to the case of a magnetic field fixed relative to the fluid or to the moving porous plate have been presented. In order to highlight the impact of the ramp motion of the porous plate on the fluid flow, it has also been compared with Couette flow between porous plates when one of the porous plates has been set into an impulsive motion.

Keywords

  • Couette flow
  • transverse magnetic field
  • suction/injection
  • MHD
  • ramp motion
  • Hartmann number
  • porous plates
Open Access

The analysis of the calculation process related to labyrinth sealing with extraction

Published Online: 07 Mar 2014
Page range: 1057 - 1066

Abstract

Abstract

The work presents a calculation process enabling one-dimensional numerical calculations of labyrinth sealing. A DSV program determines the thermodynamic parameters of gas in the sealing chambers with extraction. The influence of the sealing length upon the stability of a matrix solution of the system of equations with the use of Cond(C) parameter is analysed. Next, the operation of the software extended with a module that enables determination of the initial pressure p0, to which the assumed mass flow for a set geometry and sealing length would correspond is discussed. The work analyzes Cond(C) and initial pressure values for various sealing lengths with an assumed leak value. The work also compares the values of static pressures on the extraction plane, as obtained from the measurements, to theoretically calculated values. The calculations and comparisons were made for various heights of incomplete sealing fissures

Keywords

  • labyrinth seals
  • turbomachines
  • fluid-flow machines
  • method of calculation labyrinth seals
Open Access

Uniqueness, reciprocity theorems and plane wave propagation in different theories of thermoelasticy

Published Online: 07 Mar 2014
Page range: 1067 - 1086

Abstract

Abstract

In this work, a compact form of different theories of thermoelasticity is considered. The governing equations for particle motion in a homogeneous isotropic thermoelastic medium are presented. Uniqueness and reciprocity theorems are proved. The plane wave propagation in a homogeneous isotropic thermoelastic medium is studied. For a three dimensional problem there exist four waves, namely a P-wave, two transverse waves (S1, S2) and a thermal wave (T). From the obtained results the different characteristics of waves such as the phase velocity and attenuation coefficient are computed numerically and presented graphically. Some special cases are also discussed.

Keywords

  • isotropic
  • thermoelasticity
  • uniqueness theorem
  • reciprocity theorem
  • plane wave
Open Access

MHD and rotation effects on flow past an accelerated vertical plate with variable temperature and mass diffusion in the presence of chemical reaction

Published Online: 07 Mar 2014
Page range: 1087 - 1097

Abstract

Abstract

An exact analysis of rotation effects on an unsteady flow of an incompressible and electrically conducting fluid past a uniformly accelerated infinite isothermal vertical plate, under the action of a transversely applied magnetic field is presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C’w. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity profiles, temperature and concentration are studied for different physical parameters such as the magnetic field parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that the velocity increases with increasing values of the thermal Grashof number or mass Grashof number. It is also observed that the velocity increases with decreasing values of the magnetic field parameter or rotation parameter Ω.

Keywords

  • rotation
  • accelerated
  • isothermal
  • vertical plate
  • heat transfer
  • diffusion
  • magnetic field
  • chemical reaction
Open Access

MHD flow of longitudinal and torsional oscillations of a circular cylinder with suction in a couple stress fluid

Published Online: 07 Mar 2014
Page range: 1099 - 1114

Abstract

Abstract

In this paper, we consider the flow an incompressible electrically conducting couple stress fluid generated by performing longitudinal and torsional oscillations of a porous circular cylinder subjected to constant suction/injection at the surface of the cylinder and in the presence of a radial magnetic field. A finite difference method is proposed to analyze the velocity components, in an infinite expansion of a couple stress fluid under vanishing couple stresses on the boundary. The effects of the magnetic parameter, couple stress parameter, Reynolds number, the ratio of couple stress viscosities parameter and suction parameter on velocity components and drag are discussed and shown graphically.

Keywords

  • longitudinal and torsional oscillations
  • drag
  • suction
  • radial magnetic field
Open Access

Effect of chemical reaction and radiation on double diffusive flow of a viscous, dissipative fluid through porous medium in a rectangular cavity with heat sources

Published Online: 07 Mar 2014
Page range: 1115 - 1150

Abstract

Abstract

In this paper, an attempt is made to discuss the combined influence of radiation and dissipation on the convective heat and mass transfer flow of a viscous fluid through a porous medium in a rectangular cavity using the Darcy model. Making use of the incompressibility, the governing non-linear coupled equations for the momentum, energy and diffusion are derived in terms of the non-dimensional stream function, temperature and concentration. The Galerkin finite element analysis with linear triangular elements is used to obtain the global stiffness matrices for the values of stream function, temperature and concentration. These coupled matrices are solved using an iterative procedure and expressions for the stream function, temperature and concentration are obtained as linear combinations of the shape functions. The behavior of temperature, concentration, the Nusselt number and Sherwood number is discussed computationally for different values of the governing parameters, such as the Rayleigh Number (Ra), heat source parameter (α), Eckert number (Ec), Schmidt Number (Sc), Soret parameter (S0), buoyancy ratio (N).

Keywords

  • heat and mass transfer flow
  • radiation
  • dissipation
  • heat sources
  • rectangular cavity
  • porous medium
Open Access

Thermal radiation and magnetic field effects on unsteady mixed convection flow and mass transfer over a porous stretching surface with heat generation

Published Online: 07 Mar 2014
Page range: 1151 - 1164

Abstract

Abstract

The effects of thermal radiation and mass transfer on an unsteady hydromagnetic boundary layer mixed convection flow along a vertical porous stretching surface with heat generation are studied. The fluid is assumed to be viscous and incompressible. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity variables. Numerical solutions of these equations are obtained by using the Runge-Kutta fourth order method along with the shooting technique. Velocity, temperature, concentration, the skin-friction coefficient, Nusselt number and Sherwood number for variations in the governing thermo physical parameters are computed, analyzed and discussed.

Keywords

  • radiation
  • mass transfer
  • stretching surface
  • magnetic field
  • heat generation
  • temperature etc.
Open Access

Anti – plane crack emanating from the interface in a bounded smart PEMO- elastic structure

Published Online: 07 Mar 2014
Page range: 1165 - 1199

Abstract

Abstract

The magnetoelectroelastic analysis of two bonded dissimilar piezo-electro-magneto-elastic ceramics with a crack perpendicular to and terminating at the interface is made. By using the Fourier integral transform (in perpendicular directions in each materials), the mixed boundary conditions and continuity conditions are transformed to a singular integral equation with generalized Cauchy kernel, the solution of which has been well studied, and classical methods are directly applicable here to obtain the closed form solution. The results are presented for a permeable crack under anti-plane shear loading and in-plane electric and magnetic loadings, as prescribed electric displacement and magnetic inductions or electric and magnetic fields. The results indicate that the magnetoelectroelastic field near the crack tip in the homogeneous PEMO- elastic ceramic is dominated by a traditional inverse square-root singularity, while the coupled field near the crack tip at the interface exhibits the singularity of the power law r--α , r being the distance from the interface crack tip and α depending on the material constants of a bimaterial. In particular, electric and magnetic fields have no singularity at the crack tip in a homogeneous solid, whereas they are singular around the interface crack tip. Numerical results are given graphically to show the effects of the material properties on the singularity order, field intensity factors and energy release rates. The results presented in this paper should have potential applications to the design of multilayered magnetoelectroelastic structures.

Keywords

  • interface
  • anti-plane shear crack
  • singularity of power law
  • field intensity factors
  • magnetoelectroelastic behaviour
  • Fourier transform
  • Cauchy singular integral equation
  • exact solution
Open Access

MHD natural convection flow with radiative heat transfer past an impulsively moving vertical plate with ramped temperature in the presence of hall current and thermal diffusion

Published Online: 07 Mar 2014
Page range: 1201 - 1220

Abstract

Abstract

An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.

Keywords

  • MHD natural convection
  • Hall current
  • ramped temperature
  • thermal diffusion
  • thermal radiation
Open Access

Surface waves in non-homogeneous, general magnetothermo, viscoelastic media of higher order

Published Online: 07 Mar 2014
Page range: 1221 - 1236

Abstract

Abstract

The aim of the present paper is to investigate surface waves in a non-homogeneous, isotropic, visco-elastic solid medium of n-th order including the time rate of strain. The theory of generalised surface waves has firstly been developed and then it has been employed to investigate particular cases of waves, viz., Stoneley, Rayleigh and Love type. The wave velocity equations have been obtained for different cases and are in well agreement with the corresponding classical result, when the effects of viscosity, temperature, magnetism as well as nonhomogeneity of the material medium are ignored.

Keywords

  • inhomogeneous media
  • variable density
  • surface waves
  • viscosity
Open Access

Effect of slip condition on viscoelastic mhd oscillatory forced convection flow in a vertical channel with heat radiation

Published Online: 07 Mar 2014
Page range: 1237 - 1248

Abstract

Abstract

In this paper an oscillatory flow of a viscoelastic, incompressible and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel plates is discussed. One of these plates is subjected to a slip-flow condition and the other to a no-slip condition. The pressure gradient in the channel oscillates with time. A magnetic field of uniform strength is applied in the direction perpendicular to the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature difference of the two plates is also assumed high enough to induce heat transfer due to radiation. A closed form analytical solution to the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters entering into the problem. A number of particular cases have been shown by dotted curves in the figures. During the analysis it is found that the physical and the mathematical formulations of the problems by Makinde and Mhone (2005), Mehmood and Ali (2007), Kumar et al. (2010) and Choudhury and Das (2012) are not correct. The correct solutions to all these important oscillatory flow problems are deduced.

Keywords

  • oscillatory
  • MHD
  • forced convection
  • viscoelastic
  • slip-flow
  • porous medium
Open Access

Response due to mechanical source in second axisymmetric problem of micropolar elastic medium

Published Online: 07 Mar 2014
Page range: 1249 - 1261

Abstract

Abstract

The second axisymmetric problem in a micropolar elastic medium has been investigated by employing an eigen value approach after applying the Laplace and the Hankel transforms. An example of infinite space with concentrated force at the origin has been presented to illustrate the application of the approach. The integral transforms have been inversed by using a numerical technique to obtain the components of microrotation, displacement, force stress and couple stress in the physical domain. The results for these quantities are given and illustratred graphically.

Keywords

  • eigen value
  • micropolar elastic medium
  • Laplace transforms
  • Hankel transforms
  • concentrated force
  • microrotation
  • Rhomberg’s integration
Open Access

Plastic limit load of ellipsoidal pressure vessel head with nozzle under internal pressure loading

Published Online: 07 Mar 2014
Page range: 1263 - 1274

Abstract

Abstract

A new method and numerical procedure for determining the plastic limit load in an ellipsoid-cylinder intersection using the elastic-plastic finite element analysis are presented. The proposed method is based on the maximum criterion of the rate of change of the relative plastic work. For the elastic-plastic analysis of the nozzle connections the 2D finite element method and plasticity theory with strain hardening are used. The results of the comparison of the plastic limit pressure obtained on the basis of different known criteria and the proposed criterion are presented. A parametric study of ellipsoidal heads with a nozzle under internal pressure loading was performed. The effects of nondimensional geometric parameters of shell intersection on the plastic limit pressure are discussed.

Keywords

  • shell intersection
  • elastic-plastic finite element analysis
  • plastic limit load
  • ellipsoidal head
  • nozzle connection
Open Access

Applying the life cycle assessment method to an analysis of the environmental impact of heat generation

Published Online: 07 Mar 2014
Page range: 1275 - 1281

Abstract

Abstract

The paper presents a method of Life Cycle Assessment (LCA) to determine the impact of the heat produced on the environment. In addition, the usefulness of this method to assess the energy sector has been shown.

This paper presents the impact of heat generation on the environment in coal power plants. A detailed analysis by the method of LCA is made to compare the environmental impact of heat generation in the Legnica Power Plant and Polkowice Power Plant.

It is pointed to the difference in the results obtained. Moreover, the causes of the reported environmental impacts are discussed. Measures are identified which will help to reduce in the future the impact of the electricity produced on the environment during the production of heat.

Keywords

  • life cycle assessment
  • energy
  • ecology
  • heat
  • power plant
Open Access

The use the of digital image correlation in a strain analysis

Published Online: 07 Mar 2014
Page range: 1283 - 1292

Abstract

Abstract

This paper provides a description of the basic principles and procedures that can be found in strain measurements by means of an experimental method known as the digital image correlation (DIC) while using the correlation system Q-400 and the evaluation software Istra4D. The second part of the paper includes the application of DIC method in strain measurements on a sample made of a PS-1A photoelastic material while using the correlation system Q-400.

Keywords

  • digital image correlation (DIC)
  • correlation system Q-400
  • software Istra4D
  • strains
19 Articles
Open Access

Closed form solutions of heat and mass transfer in the flow of a MHD visco-elastic fluid over a porous stretching sheet

Published Online: 07 Mar 2014
Page range: 989 - 1002

Abstract

Abstract

The problem of heat and mass transfer in a visco-elastic fluid flow over a stretching sheet in the presence of a uniform magnetic field is examined. The important physical quantities such as the skin friction coefficient, heat transfer co-efficient and the mass transfer co-efficient are determined. It is found that the heat and mass transfer distribution decreases with the increasing values of the visco-elastic parameter k1.

Keywords

  • heat and mass transfer
  • MHD flow
  • porous stretching sheet
  • visco-elastic fluid
Open Access

Boundary layer flow and heat transfer over a permeable shrinking cylinder with surface mass transfer

Published Online: 07 Mar 2014
Page range: 1003 - 1012

Abstract

Abstract

In the present paper, the axisymmetric boundary layer flow and heat transfer past a permeable shrinking cylinder subject to surface mass transfer is studied. The similarity transformations are adopted to convert the governing partial differential equations for the flow and heat transfer into the nonlinear self-similar ordinary differential equations and then solved by a finite difference method using the quasilinearization technique. From the current investigation, it is found that the velocity in the boundary layer region decreases with the curvature parameter and increases with suction mass transfer. Moreover, with the increase of the curvature parameter, the suction parameter and Prandtl number, the heat transfer is enhanced.

Keywords

  • boundary layer
  • heat transfer
  • shrinking cylinder
  • mass suction
Open Access

Wave propagation in micropolar monoclinic thermoelastic half space

Published Online: 07 Mar 2014
Page range: 1013 - 1023

Abstract

Abstract

Propagation of waves in a micropolar monoclinic medium possessing hermoelastic properties based on the Lord- Shulman (L-S),Green and Lindsay (G-L) and Coupled thermoelasticty (C-T) theories is discussed. The investigation is divided into two sections, viz., plane strain and anti-plane strain problem. After developing the solution, the phase velocities and attenuation quality factor have been derived and computed numerically. The numerical results have been plotted graphically.

Keywords

  • micropolar
  • monoclinic
  • generalized thermoelastic
Open Access

Three-dimensional oscillating flow between two parallel plates through a porous medium

Published Online: 07 Mar 2014
Page range: 1025 - 1037

Abstract

Abstract

An unsteady Couette flow between two parallel plates when upper plates oscillates in its own plane and is subjected to a constant suction and the lower plate to a injection velocity distribution through the porous medium has been analyzed. The approximate solution has been obtained using perturbation technique. It is seen that the primary velocity increases whereas the secondary velocity decreases with an increase in permeability parameter. It is also found that the primary velocity increases with an increase in the Reynolds number as well as the suction parameter. The magnitude of the secondary velocity increases near the stationary plate but decreases near the oscillating plate with an increase in the Reynolds number. Whereas, it increases with an increase in the suction parameter.

Keywords

  • Couette flow
  • three-dimensional
  • injection
  • suction
  • transverse sinusoidal
Open Access

Unsteady hydromagnetic couette flow due to ramped motion of one of the porous plates

Published Online: 07 Mar 2014
Page range: 1039 - 1056

Abstract

Abstract

An unsteady flow formation in Couette motion of an electrically conducting fluid subject to transverse magnetic field has been analyzed in the presence of suction/injection through the porous plates when one of the porous plates is in ramped motion. It is assumed that the porous plates are uniformly permeable and the fluid is entering the flow region through one of the porous plates at same rate as it is leaving through the other porous plate. The resulting boundary value problem has been solved exactly under the assumption of a negligible induced magnetic field, external electric field and pressure gradient. Unified closed form expressions for the velocity field and skin-friction corresponding to the case of a magnetic field fixed relative to the fluid or to the moving porous plate have been presented. In order to highlight the impact of the ramp motion of the porous plate on the fluid flow, it has also been compared with Couette flow between porous plates when one of the porous plates has been set into an impulsive motion.

Keywords

  • Couette flow
  • transverse magnetic field
  • suction/injection
  • MHD
  • ramp motion
  • Hartmann number
  • porous plates
Open Access

The analysis of the calculation process related to labyrinth sealing with extraction

Published Online: 07 Mar 2014
Page range: 1057 - 1066

Abstract

Abstract

The work presents a calculation process enabling one-dimensional numerical calculations of labyrinth sealing. A DSV program determines the thermodynamic parameters of gas in the sealing chambers with extraction. The influence of the sealing length upon the stability of a matrix solution of the system of equations with the use of Cond(C) parameter is analysed. Next, the operation of the software extended with a module that enables determination of the initial pressure p0, to which the assumed mass flow for a set geometry and sealing length would correspond is discussed. The work analyzes Cond(C) and initial pressure values for various sealing lengths with an assumed leak value. The work also compares the values of static pressures on the extraction plane, as obtained from the measurements, to theoretically calculated values. The calculations and comparisons were made for various heights of incomplete sealing fissures

Keywords

  • labyrinth seals
  • turbomachines
  • fluid-flow machines
  • method of calculation labyrinth seals
Open Access

Uniqueness, reciprocity theorems and plane wave propagation in different theories of thermoelasticy

Published Online: 07 Mar 2014
Page range: 1067 - 1086

Abstract

Abstract

In this work, a compact form of different theories of thermoelasticity is considered. The governing equations for particle motion in a homogeneous isotropic thermoelastic medium are presented. Uniqueness and reciprocity theorems are proved. The plane wave propagation in a homogeneous isotropic thermoelastic medium is studied. For a three dimensional problem there exist four waves, namely a P-wave, two transverse waves (S1, S2) and a thermal wave (T). From the obtained results the different characteristics of waves such as the phase velocity and attenuation coefficient are computed numerically and presented graphically. Some special cases are also discussed.

Keywords

  • isotropic
  • thermoelasticity
  • uniqueness theorem
  • reciprocity theorem
  • plane wave
Open Access

MHD and rotation effects on flow past an accelerated vertical plate with variable temperature and mass diffusion in the presence of chemical reaction

Published Online: 07 Mar 2014
Page range: 1087 - 1097

Abstract

Abstract

An exact analysis of rotation effects on an unsteady flow of an incompressible and electrically conducting fluid past a uniformly accelerated infinite isothermal vertical plate, under the action of a transversely applied magnetic field is presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C’w. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity profiles, temperature and concentration are studied for different physical parameters such as the magnetic field parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that the velocity increases with increasing values of the thermal Grashof number or mass Grashof number. It is also observed that the velocity increases with decreasing values of the magnetic field parameter or rotation parameter Ω.

Keywords

  • rotation
  • accelerated
  • isothermal
  • vertical plate
  • heat transfer
  • diffusion
  • magnetic field
  • chemical reaction
Open Access

MHD flow of longitudinal and torsional oscillations of a circular cylinder with suction in a couple stress fluid

Published Online: 07 Mar 2014
Page range: 1099 - 1114

Abstract

Abstract

In this paper, we consider the flow an incompressible electrically conducting couple stress fluid generated by performing longitudinal and torsional oscillations of a porous circular cylinder subjected to constant suction/injection at the surface of the cylinder and in the presence of a radial magnetic field. A finite difference method is proposed to analyze the velocity components, in an infinite expansion of a couple stress fluid under vanishing couple stresses on the boundary. The effects of the magnetic parameter, couple stress parameter, Reynolds number, the ratio of couple stress viscosities parameter and suction parameter on velocity components and drag are discussed and shown graphically.

Keywords

  • longitudinal and torsional oscillations
  • drag
  • suction
  • radial magnetic field
Open Access

Effect of chemical reaction and radiation on double diffusive flow of a viscous, dissipative fluid through porous medium in a rectangular cavity with heat sources

Published Online: 07 Mar 2014
Page range: 1115 - 1150

Abstract

Abstract

In this paper, an attempt is made to discuss the combined influence of radiation and dissipation on the convective heat and mass transfer flow of a viscous fluid through a porous medium in a rectangular cavity using the Darcy model. Making use of the incompressibility, the governing non-linear coupled equations for the momentum, energy and diffusion are derived in terms of the non-dimensional stream function, temperature and concentration. The Galerkin finite element analysis with linear triangular elements is used to obtain the global stiffness matrices for the values of stream function, temperature and concentration. These coupled matrices are solved using an iterative procedure and expressions for the stream function, temperature and concentration are obtained as linear combinations of the shape functions. The behavior of temperature, concentration, the Nusselt number and Sherwood number is discussed computationally for different values of the governing parameters, such as the Rayleigh Number (Ra), heat source parameter (α), Eckert number (Ec), Schmidt Number (Sc), Soret parameter (S0), buoyancy ratio (N).

Keywords

  • heat and mass transfer flow
  • radiation
  • dissipation
  • heat sources
  • rectangular cavity
  • porous medium
Open Access

Thermal radiation and magnetic field effects on unsteady mixed convection flow and mass transfer over a porous stretching surface with heat generation

Published Online: 07 Mar 2014
Page range: 1151 - 1164

Abstract

Abstract

The effects of thermal radiation and mass transfer on an unsteady hydromagnetic boundary layer mixed convection flow along a vertical porous stretching surface with heat generation are studied. The fluid is assumed to be viscous and incompressible. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity variables. Numerical solutions of these equations are obtained by using the Runge-Kutta fourth order method along with the shooting technique. Velocity, temperature, concentration, the skin-friction coefficient, Nusselt number and Sherwood number for variations in the governing thermo physical parameters are computed, analyzed and discussed.

Keywords

  • radiation
  • mass transfer
  • stretching surface
  • magnetic field
  • heat generation
  • temperature etc.
Open Access

Anti – plane crack emanating from the interface in a bounded smart PEMO- elastic structure

Published Online: 07 Mar 2014
Page range: 1165 - 1199

Abstract

Abstract

The magnetoelectroelastic analysis of two bonded dissimilar piezo-electro-magneto-elastic ceramics with a crack perpendicular to and terminating at the interface is made. By using the Fourier integral transform (in perpendicular directions in each materials), the mixed boundary conditions and continuity conditions are transformed to a singular integral equation with generalized Cauchy kernel, the solution of which has been well studied, and classical methods are directly applicable here to obtain the closed form solution. The results are presented for a permeable crack under anti-plane shear loading and in-plane electric and magnetic loadings, as prescribed electric displacement and magnetic inductions or electric and magnetic fields. The results indicate that the magnetoelectroelastic field near the crack tip in the homogeneous PEMO- elastic ceramic is dominated by a traditional inverse square-root singularity, while the coupled field near the crack tip at the interface exhibits the singularity of the power law r--α , r being the distance from the interface crack tip and α depending on the material constants of a bimaterial. In particular, electric and magnetic fields have no singularity at the crack tip in a homogeneous solid, whereas they are singular around the interface crack tip. Numerical results are given graphically to show the effects of the material properties on the singularity order, field intensity factors and energy release rates. The results presented in this paper should have potential applications to the design of multilayered magnetoelectroelastic structures.

Keywords

  • interface
  • anti-plane shear crack
  • singularity of power law
  • field intensity factors
  • magnetoelectroelastic behaviour
  • Fourier transform
  • Cauchy singular integral equation
  • exact solution
Open Access

MHD natural convection flow with radiative heat transfer past an impulsively moving vertical plate with ramped temperature in the presence of hall current and thermal diffusion

Published Online: 07 Mar 2014
Page range: 1201 - 1220

Abstract

Abstract

An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.

Keywords

  • MHD natural convection
  • Hall current
  • ramped temperature
  • thermal diffusion
  • thermal radiation
Open Access

Surface waves in non-homogeneous, general magnetothermo, viscoelastic media of higher order

Published Online: 07 Mar 2014
Page range: 1221 - 1236

Abstract

Abstract

The aim of the present paper is to investigate surface waves in a non-homogeneous, isotropic, visco-elastic solid medium of n-th order including the time rate of strain. The theory of generalised surface waves has firstly been developed and then it has been employed to investigate particular cases of waves, viz., Stoneley, Rayleigh and Love type. The wave velocity equations have been obtained for different cases and are in well agreement with the corresponding classical result, when the effects of viscosity, temperature, magnetism as well as nonhomogeneity of the material medium are ignored.

Keywords

  • inhomogeneous media
  • variable density
  • surface waves
  • viscosity
Open Access

Effect of slip condition on viscoelastic mhd oscillatory forced convection flow in a vertical channel with heat radiation

Published Online: 07 Mar 2014
Page range: 1237 - 1248

Abstract

Abstract

In this paper an oscillatory flow of a viscoelastic, incompressible and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel plates is discussed. One of these plates is subjected to a slip-flow condition and the other to a no-slip condition. The pressure gradient in the channel oscillates with time. A magnetic field of uniform strength is applied in the direction perpendicular to the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature difference of the two plates is also assumed high enough to induce heat transfer due to radiation. A closed form analytical solution to the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters entering into the problem. A number of particular cases have been shown by dotted curves in the figures. During the analysis it is found that the physical and the mathematical formulations of the problems by Makinde and Mhone (2005), Mehmood and Ali (2007), Kumar et al. (2010) and Choudhury and Das (2012) are not correct. The correct solutions to all these important oscillatory flow problems are deduced.

Keywords

  • oscillatory
  • MHD
  • forced convection
  • viscoelastic
  • slip-flow
  • porous medium
Open Access

Response due to mechanical source in second axisymmetric problem of micropolar elastic medium

Published Online: 07 Mar 2014
Page range: 1249 - 1261

Abstract

Abstract

The second axisymmetric problem in a micropolar elastic medium has been investigated by employing an eigen value approach after applying the Laplace and the Hankel transforms. An example of infinite space with concentrated force at the origin has been presented to illustrate the application of the approach. The integral transforms have been inversed by using a numerical technique to obtain the components of microrotation, displacement, force stress and couple stress in the physical domain. The results for these quantities are given and illustratred graphically.

Keywords

  • eigen value
  • micropolar elastic medium
  • Laplace transforms
  • Hankel transforms
  • concentrated force
  • microrotation
  • Rhomberg’s integration
Open Access

Plastic limit load of ellipsoidal pressure vessel head with nozzle under internal pressure loading

Published Online: 07 Mar 2014
Page range: 1263 - 1274

Abstract

Abstract

A new method and numerical procedure for determining the plastic limit load in an ellipsoid-cylinder intersection using the elastic-plastic finite element analysis are presented. The proposed method is based on the maximum criterion of the rate of change of the relative plastic work. For the elastic-plastic analysis of the nozzle connections the 2D finite element method and plasticity theory with strain hardening are used. The results of the comparison of the plastic limit pressure obtained on the basis of different known criteria and the proposed criterion are presented. A parametric study of ellipsoidal heads with a nozzle under internal pressure loading was performed. The effects of nondimensional geometric parameters of shell intersection on the plastic limit pressure are discussed.

Keywords

  • shell intersection
  • elastic-plastic finite element analysis
  • plastic limit load
  • ellipsoidal head
  • nozzle connection
Open Access

Applying the life cycle assessment method to an analysis of the environmental impact of heat generation

Published Online: 07 Mar 2014
Page range: 1275 - 1281

Abstract

Abstract

The paper presents a method of Life Cycle Assessment (LCA) to determine the impact of the heat produced on the environment. In addition, the usefulness of this method to assess the energy sector has been shown.

This paper presents the impact of heat generation on the environment in coal power plants. A detailed analysis by the method of LCA is made to compare the environmental impact of heat generation in the Legnica Power Plant and Polkowice Power Plant.

It is pointed to the difference in the results obtained. Moreover, the causes of the reported environmental impacts are discussed. Measures are identified which will help to reduce in the future the impact of the electricity produced on the environment during the production of heat.

Keywords

  • life cycle assessment
  • energy
  • ecology
  • heat
  • power plant
Open Access

The use the of digital image correlation in a strain analysis

Published Online: 07 Mar 2014
Page range: 1283 - 1292

Abstract

Abstract

This paper provides a description of the basic principles and procedures that can be found in strain measurements by means of an experimental method known as the digital image correlation (DIC) while using the correlation system Q-400 and the evaluation software Istra4D. The second part of the paper includes the application of DIC method in strain measurements on a sample made of a PS-1A photoelastic material while using the correlation system Q-400.

Keywords

  • digital image correlation (DIC)
  • correlation system Q-400
  • software Istra4D
  • strains

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