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

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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)

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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 3 (August 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

23 Articles
Open Access

Variable Gravity Effects on Thermal Instability of Nanofluid in Anisotropic Porous Medium

Published Online: 06 Sep 2013
Page range: 631 - 642

Abstract

Abstract

In this paper, we study the effects of variable gravity on thermal instability in a horizontal layer of a nanofluid in an anisotropic porous medium. Darcy model been used for the porous medium. Also, it incorporates the effect of Brownian motion along with thermophoresis. The normal mode technique is used to find the confinement between two free boundaries. The expression of the Rayleigh number has been derived, and the effects of variable gravity and anisotropic parameters on the Rayleigh number have been presented graphically

Keywords

  • nanofluid
  • anisotropic porous medium
  • Rayleigh number
  • variable gravity
Open Access

Radiation Effects on Oscillating Vertical Plate with Uniform Heat and Mass Flux

Published Online: 06 Sep 2013
Page range: 643 - 652

Abstract

Abstract

Thermal radiation effects on flow past an impulsively started infinite vertical oscillating plate with uniform heat and mass flux is studied. The fluid considered here is a gray, absorbing-emitting radiation but a nonscattering medium. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity, temperature and concentration are studied for different physical parameters such as the radiation parameter, phase angle, Schmidt number and time. The variation of the skin-friction for different values of the parameters is also shown in a table

Keywords

  • oscillating vertical plate
  • radiation
  • heat and mass flux
Open Access

Pattern of Stress-Strain Accumulation due to a Long Dipslip Fault Movement in a Viscoelastic Layered Model of The Lithosphere–Asthenosphere System

Published Online: 06 Sep 2013
Page range: 653 - 670

Abstract

Abstract

The process of stress accumulation near earthquake faults during the aseismic period in between two major seismic events in seismically active regions has become a subject of research during the last few decades. In the present paper a long dip -slip fault is taken to be situated in a viscoelastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons, e.g., mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving the associated boundary value problem with the help of integral transformation and Green's function method. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme

Keywords

  • aseismic period
  • dip-slip fault
  • earthquake prediction
  • stress accumulation
  • viscoelastic-layered model
Open Access

Reflection of Waves in Initially Stressed Transversely Isotropic Fibre-Reinforced Thermoelastic Medium

Published Online: 06 Sep 2013
Page range: 671 - 685

Abstract

Abstract

The present investigation deals with the reflection of plane periodic waves incident at the surface of a homogeneous initially stressed transversely isotropic fibrereinforced thermoelastic medium. The wave equations are solved by imposing proper conditions on displacements, stresses and temperature distribution. Numerically simulated results have been depicted graphically for different angles of incidence with respect to frequency. Some special cases of interest have also been deduced from the present investigation

Keywords

  • reflection
  • initially stressed
  • fiber-reinforced
  • transversely isotropic
Open Access

A Concept of the Differentially Driven Three Wheeled Robot

Published Online: 06 Sep 2013
Page range: 687 - 698

Abstract

Abstract

The paper deals with the concept of a differentially driven three wheeled robot. The main task for the robot is to follow the navigation black line on white ground. The robot also contains anti-collision sensors for avoiding obstacles on track. Students learn how to deal with signals from sensors and how to control DC motors. Students work with the controller and develop the locomotion algorithm and can attend a competition

Keywords

  • robot
  • education
  • wheeled locomotion
  • sensor
  • mechatronics
Open Access

Unsteady Two-Layered Fluid Flow and Heat Transfer of Conducting Fluids in a Channel Between Parallel Porous Plates Under Transverse Magnetic Field

Published Online: 06 Sep 2013
Page range: 699 - 726

Abstract

Abstract

The unsteady magnetohydrodynamic flow of two immiscible fluids in a horizontal channel bounded by two parallel porous isothermal plates in the presence of an applied magnetic and electric field is investigated. The flow is driven by a constant uniform pressure gradient in the channel bounded by two parallel insulating plates, one being stationary and the other oscillating, when both fluids are considered as electrically conducting. Also, both fluids are assumed to be incompressible with variable properties, viz. different viscosities, thermal and electrical conductivities. The transport properties of the two fluids are taken to be constant and the bounding plates are maintained at constant and equal temperatures. The governing equations are partial in nature, which are then reduced to the ordinary linear differential equations using two-term series. Closed form solutions for velocity and temperature distributions are obtained in both fluid regions of the channel. Profiles of these solutions are plotted to discuss the effect on the flow and heat transfer characteristics, and their dependence on the governing parameters involved, such as the Hartmann number, porous parameter, ratios of the viscosities, heights, electrical and thermal conductivities

Keywords

  • magnetohydrodynamics
  • two-layered fluid flow/immiscible fluids
  • unsteady flow
  • oscillatory motion
  • heat transfer
  • porous plates
Open Access

Chemical Reaction Effects on MHD Flow Past a Linearly Accelerated Vertical Plate with Variable Temperature and Mass Diffusion in the Presence of Thermal Radiation

Published Online: 06 Sep 2013
Page range: 727 - 737

Abstract

Abstract

An exact solution of first order chemical reaction effects on a radiative flow past a linearly accelerated infinite isothermal vertical plate with variable mass diffusion, under the action of a transversely applied magnetic field has been presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C'w linearly with time. The dimensionless governing equations are tackled using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the magnetic field parameter, radiation parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that velocity increases with decreasing magnetic field parameter or radiation parameter. But the trend is just reversed with respect to the chemical reaction parameter

Keywords

  • accelerated
  • isothermal
  • radiation
  • vertical plate
  • heat and mass transfer
  • magnetic field
  • chemical reaction
Open Access

Heat Transfer of Viscoelastic Fluid Flow due to Nonlinear Stretching Sheet with Internal Heat Source

Published Online: 06 Sep 2013
Page range: 739 - 760

Abstract

Abstract

In the present paper, a viscoelastic boundary layer flow and heat transfer over an exponentially stretching continuous sheet in the presence of a heat source/sink has been examined. Loss of energy due to viscous dissipation of the non-Newtonian fluid has been taken into account in this study. Approximate analytical local similar solutions of the highly non-linear momentum equation are obtained for velocity distribution by transforming the equation into Riccati-type and then solving this sequentially. Accuracy of the zero-order analytical solutions for the stream function and velocity are verified by numerical solutions obtained by employing the Runge-Kutta fourth order method involving shooting. Similarity solutions of the temperature equation for non-isothermal boundary conditions are obtained in the form of confluent hypergeometric functions. The effect of various physical parameters on the local skin-friction coefficient and heat transfer characteristics are discussed in detail. It is seen that the rate of heat transfer from the stretching sheet to the fluid can be controlled by suitably choosing the values of the Prandtl number Pr and local Eckert number E, local viscioelastic parameter k*1 and local heat source/ sink parameter β*

Keywords

  • viscoelastic fluid
  • boundary layer flow
  • exponential stretching sheet
  • heat source/sink
  • heat transfer and skin friction
Open Access

Numerical Solution of Non-Newtonian Fluids Flow Past an Accelerated Vertical Infinite Plate in the Presence of Free Convection Currents

Published Online: 06 Sep 2013
Page range: 761 - 777

Abstract

Abstract

A similarity analysis of non-Newtonian fluid flow past an accelerated vertical infinite plate in the presence of free convection current is carried out. A group theoretic generalized dimensional analysis is employed to achieve the governing non-linear ordinary differential equations in the most general form. Numerical solutions of these equations are given with the plot of their velocity profiles with the effects of Pr-Prandtl number and Gr-Grashof number

Keywords

  • non-Newtonian fluids
  • convection currents
  • similarity analysis
Open Access

Flow and Heat Transfer at a Nonlinearly Shrinking Porous Sheet:The Case of Asymptotically Large Powerlaw Shrinking Rates

Published Online: 06 Sep 2013
Page range: 779 - 791

Abstract

Abstract

The boundary layer flow and heat transfer of a viscous fluid over a nonlinear permeable shrinking sheet in a thermally stratified environment is considered. The sheet is assumed to shrink in its own plane with an arbitrary power-law velocity proportional to the distance from the stagnation point. The governing differential equations are first transformed into ordinary differential equations by introducing a new similarity transformation. This is different from the transform commonly used in the literature in that it permits numerical solutions even for asymptotically large values of the power-law index, m. The coupled non-linear boundary value problem is solved numerically by an implicit finite difference scheme known as the Keller- Box method. Numerical computations are performed for a wide variety of power-law parameters (1 < m < 100,000) so as to capture the effects of the thermally stratified environment on the velocity and temperature fields. The numerical solutions are presented through a number of graphs and tables. Numerical results for the skin-friction coefficient and the Nusselt number are tabulated for various values of the pertinent parameters.

Keywords

  • boundary layer flow
  • porous shrinking sheet
  • Keller-Box method
  • similarity solutions
  • heat transfer
Open Access

Response of Non-Linear Shock Absorbers-Boundary Value Problem Analysis

Published Online: 06 Sep 2013
Page range: 793 - 814

Abstract

Abstract

A nonlinear boundary value problem of two degrees-of-freedom (DOF) untuned vibration damper systems using nonlinear springs and dampers has been numerically studied. As far as untuned damper is concerned, sixteen different combinations of linear and nonlinear springs and dampers have been comprehensively analyzed taking into account transient terms. For different cases, a comparative study is made for response versus time for different spring and damper types at three important frequency ratios: one at r = 1, one at r > 1 and one at r <1. The response of the system is changed because of the spring and damper nonlinearities; the change is different for different cases. Accordingly, an initially stable absorber may become unstable with time and vice versa. The analysis also shows that higher nonlinearity terms make the system more unstable. Numerical simulation includes transient vibrations. Although problems are much more complicated compared to those for a tuned absorber, a comparison of the results generated by the present numerical scheme with the exact one shows quite a reasonable agreement

Keywords

  • shock absorber
  • untuned vibration damper
  • frequency ratios
  • non-linear springs
  • non-linear dampers
  • stability
  • boundary value problem
  • multisegment method of integration
Open Access

Interactions due to Moving Heat Sources in Generalized Thermoelastic Half-Space using L-S Model

Published Online: 06 Sep 2013
Page range: 815 - 831

Abstract

Abstract

A one-dimensional problem for a homogeneous, isotropic and thermoelastic half-space subjected to a moving plane of heat source on the boundary of the space, which is traction free, is considered in the context of Lord- Shulaman model (L-S model) of thermoelasticity. The Laplace transform and eigenvalue approach techniques are used to solve the resulting non-dimensional coupled equations. Numerical results for the temperature, thermal stress, and displacement distributions are represented graphically and discussed

Keywords

  • generalized thrmoelasticity
  • L-S model
  • elastic half-space
  • moving heat sources
  • eigenvalue approach
Open Access

Effects of Chemical Reaction on Magneto-Micropolar Fluid Flow from a Radiative Surface with Variable Permeability

Published Online: 06 Sep 2013
Page range: 833 - 851

Abstract

Abstract

This paper presents a study of a hydromagnetic free convection flow of an electrically conducting micropolar fluid past a vertical plate through a porous medium with a heat source, taking into account the homogeneous chemical reaction of first order. A uniform magnetic field has also been considered in the study which acts perpendicular to the porous surface of the above plate. The analysis has been done by assuming varying permeability of the medium and the Rosseland approximation has been used to describe the radiative heat flux in the energy equation. Numerical results are presented graphically in the form of velocity, micro- rotation, concentration and temperature profiles, the skin-friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall for different material parameters. The study clearly demonstrates how a chemical reaction influences the above parameters under given conditions

Keywords

  • chemical reaction
  • micro-polar fluid
  • micro-rotation
  • magneto-hydrodynamics
  • heat and mass transfer
Open Access

Exact Solution Of MHD Mixed Convection Periodic Flow In A Rotating Vertical Channel With Heat Radiation

Published Online: 06 Sep 2013
Page range: 853 - 869

Abstract

Abstract

Magnetohydrodynamic (MHD) mixed convection flow of a viscous, incompressible and electrically conducting fluid in a vertical channel is analyzed analytically. A magnetic field of uniform strength is applied perpendicular to the planes of the channel walls. The fluid is acted upon by a periodic variation of the pressure gradient in the vertically upward direction. The temperature of one of the plates is non-uniform and the temperature difference of the walls of the channel is high enough to induce heat transfer due to radiation. The fluid and the channel rotate in unison with an angular velocity about the axis normal to the plates of the channel. An exact analytical solution of the problem is obtained. Two cases of small and large rotation have been considered to assess the effects of different parameters involved in the flow problem. The velocity field, the amplitude and the phase angle of the shear stress are shown graphically and discussed in detail. During analysis it is found that the flow problem studied by Makinde and Mhone (2005) is incorrect physically and mathematically

Keywords

  • periodic flow
  • mixed convection
  • magnetohydrodynamic (MHD)
  • rotating system
  • heat radiation
Open Access

Hall Effect on Thermal Instability of Viscoelastic Dusty Fluid in Porous Medium

Published Online: 06 Sep 2013
Page range: 871 - 886

Abstract

Abstract

The effect of Hall currents and suspended dusty particles on the hydromagnetic stability of a compressible, electrically conducting Rivlin-Ericksen elastico viscous fluid in a porous medium is considered. Following the linearized stability theory and normal mode analysis the dispersion relation is obtained. For the case of stationary convection, Hall currents and suspended particles are found to have destabilizing effects whereas compressibility and magnetic field have stabilizing effects on the system. The medium permeability, however, has stabilizing and destabilizing effects on thermal instability in contrast to its destabilizing effect in the absence of the magnetic field. The critical Rayleigh numbers and the wave numbers of the associated disturbances for the onset of instability as stationary convection are obtained and the behavior of various parameters on critical thermal Rayleigh numbers are depicted graphically. The magnetic field, Hall currents and viscoelasticity parameter are found to introduce oscillatory modes in the systems, which did not exist in the absence of these parameters

Keywords

  • thermal instability
  • Rivlin-Ericksen viscoelastic fluid
  • suspended particles
  • Hall current effect
  • porous medium
Open Access

Static, Vibration and Buckling Analysis of Skew Composite and Sandwich Plates Under Thermo Mechanical Loading

Published Online: 06 Sep 2013
Page range: 887 - 898

Abstract

Abstract

Static, vibration and buckling behavior of laminated composite and sandwich skew plates is studied using an efficient C0 FE model developed based on refined higher order zigzag theory. The C0 FE model satisfies the interlaminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model, the first derivatives of transverse displacement have been treated as independent variables to overcome the problem of C1 continuity associated with the plate theory. The C0 continuity of the present element is compensated in the stiffness matrix formulation by adding a suitable term. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature is made consistent with the total strain field by using field consistent approach. Numerical results are presented for different static, vibration and buckling problems by applying the FE model under thermo mechanical loading, where a nine noded C0 continuous isoparametric element is used. It is observed that there are very few results available in the literature on laminated composite and sandwich skew plates based on refined theories. As such many new results are also generated for future reference

Keywords

  • skew plate
  • finite element
  • refined theory
  • thermal load
Open Access

Effect of Vertical Vibrations on the Onset of Binary Convection

Published Online: 06 Sep 2013
Page range: 899 - 910

Abstract

Abstract

In the present work the linear stability analysis of double diffusive convection in a binary fluid layer is performed. The major intention of this study is to investigate the influence of time-periodic vertical vibrations on the onset threshold. A regular perturbation method is used to compute the critical Rayleigh number and wave number. A closed form expression for the shift in the critical Rayleigh number is calculated as a function of frequency of modulation, the solute Rayleigh number, Lewis number, and Prandtl number. These parameters are found to have a significant influence on the onset criterion; therefore the effective control of convection is achieved by proper tuning of these parameters. Vertical vibrations are found to enhance the stability of a binary fluid layer heated and salted from below. The results of this study are useful in the areas of crystal growth in micro-gravity conditions and also in material processing industries where vertical vibrations are involved

Keywords

  • gravity modulation
  • g-jitter
  • double diffusive convection
  • perturbation method
Open Access

Probabilistic Study of Bone Remodeling Using Finite Element Analysis

Published Online: 06 Sep 2013
Page range: 911 - 921

Abstract

Abstract

The dynamic bone remodeling process is a computationally challenging research area that struggles to understand the actual mechanisms. It has been observed that a mechanical stimulus in the bone greatly affects the remodeling process. A 3D finite element model of a femur is created and a probabilistic analysis is performed on the model. The probabilistic analysis measures the sensitivities of various parameters related to the material properties, geometric properties, and the three load cases defined as Single Leg Stance, Abduction, and Adduction. The sensitivity of each parameter is based on the calculated maximum mechanical stimulus and analyzed at various values of probabilities ranging from 0.001 to 0.999. The analysis showed that the parameters associated with the Single Leg Stance load case had the highest sensitivity with a probability of 0.99 and the angle of the force applied to the joint of the proximal femur had the overall highest sensitivity

Keywords

  • probabilistic analysis
  • bone remodeling
  • finite element analysis
Open Access

Identification of Steady and Non-Steady Gait of Humanexoskeleton Walking System

Published Online: 06 Sep 2013
Page range: 923 - 933

Abstract

Abstract

In this paper a method of analysis of exoskeleton multistep locomotion was presented by using a computer with the preinstalled DChC program. The paper also presents a way to analytically calculate the “,motion indicator”, as well as the algorithm calculating its two derivatives. The algorithm developed by the author processes data collected from the investigation and then a program presents the obtained final results. Research into steady and non-steady multistep locomotion can be used to design two-legged robots of DAR type and exoskeleton control system

Keywords

  • identification
  • steady gait
  • non-steady gait
  • exoskeleton
Open Access

Non-Perturbative Solution for Hydromagnetic Flow Over a Linearly Stretching Sheet

Published Online: 06 Sep 2013
Page range: 935 - 943

Abstract

Abstract

In this paper, the Adomian decomposition method with Padé approximants are integrated to study the boundary layer flow of a conducting fluid past a linearly stretching sheet under the action of a transversely imposed magnetic field. A closed form power series solution based on Adomian polynomials is obtained for the similarity nonlinear ordinary differential equation modelling the problem. In order to satisfy the farfield condition, the Adomian power series is converted to diagonal Padé approximants and evaluated. The results obtained using ADM-Padé are remarkably accurate compared with the numerical results. The proposed technique can be easily employed to solve a wide range of nonlinear boundary value problems

Keywords

  • stretching sheet
  • hydromagnetic flow
  • ADM-Padé
  • numerical solution
Open Access

Mass Transfer with Chemical Reaction on Flow Past an Accelerated Vertical Plate with Variable Temperature and Thermal Radiation

Published Online: 06 Sep 2013
Page range: 945 - 953

Abstract

Abstract

An exact solution of an unsteady radiative flow past a uniformly accelerated infinite vertical plate with variable temperature and mass diffusion is presented here, taking into account the homogeneous chemical reaction of first order. The plate temperature as well as concentration near the plate is raised linearly with time. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number, radiation parameter, chemical reaction parameter and time. It is observed that the velocity increases with increasing values of the thermal Grashof number or mass Grashof number. But the trend is just reversed with respect to the thermal radiation parameter. It is also observed that the velocity increases with the decreasing chemical reaction parameter

Keywords

  • linearly accelerated
  • chemical reaction
  • radiation
  • heat and mass transfer
Open Access

A New Analytical Procedure for Solving the Non-Linear Differential Equation Arising in the Stretching Sheet Problem

Published Online: 06 Sep 2013
Page range: 955 - 964

Abstract

Abstract

The paper discusses a new analytical procedure for solving the non-linear boundary layer equation arising in a linear stretching sheet problem involving a Newtonian/non-Newtonian liquid. On using a technique akin to perturbation the problem gives rise to a system of non-linear governing differential equations that are solved exactly. An analytical expression is obtained for the stream function and velocity as a function of the stretching parameters. The Clairaut equation is obtained on consideration of consistency and its solution is shown to be that of the stretching sheet boundary layer equation. The present study throws light on the analytical solution of a class of boundary layer equations arising in the stretching sheet problem

Keywords

  • differential equations
  • Clairaut equation
  • Newtonian liquid
  • stretching sheet
  • suction/injection
Open Access

Projective Synchronization of Chaotic Systems Via Backstepping Design

Published Online: 06 Sep 2013
Page range: 965 - 973

Abstract

Abstract

Chaos synchronization of discrete dynamical systems is investigated. An algorithm is proposed for projective synchronization of chaotic 2D Duffing map and chaotic Tinkerbell map. The control law was derived from the Lyapunov stability theory. Numerical simulation results are presented to verify the effectiveness of the proposed algorithm

Keywords

  • Lyapunov function
  • projective synchronization
  • backstepping
  • design
23 Articles
Open Access

Variable Gravity Effects on Thermal Instability of Nanofluid in Anisotropic Porous Medium

Published Online: 06 Sep 2013
Page range: 631 - 642

Abstract

Abstract

In this paper, we study the effects of variable gravity on thermal instability in a horizontal layer of a nanofluid in an anisotropic porous medium. Darcy model been used for the porous medium. Also, it incorporates the effect of Brownian motion along with thermophoresis. The normal mode technique is used to find the confinement between two free boundaries. The expression of the Rayleigh number has been derived, and the effects of variable gravity and anisotropic parameters on the Rayleigh number have been presented graphically

Keywords

  • nanofluid
  • anisotropic porous medium
  • Rayleigh number
  • variable gravity
Open Access

Radiation Effects on Oscillating Vertical Plate with Uniform Heat and Mass Flux

Published Online: 06 Sep 2013
Page range: 643 - 652

Abstract

Abstract

Thermal radiation effects on flow past an impulsively started infinite vertical oscillating plate with uniform heat and mass flux is studied. The fluid considered here is a gray, absorbing-emitting radiation but a nonscattering medium. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity, temperature and concentration are studied for different physical parameters such as the radiation parameter, phase angle, Schmidt number and time. The variation of the skin-friction for different values of the parameters is also shown in a table

Keywords

  • oscillating vertical plate
  • radiation
  • heat and mass flux
Open Access

Pattern of Stress-Strain Accumulation due to a Long Dipslip Fault Movement in a Viscoelastic Layered Model of The Lithosphere–Asthenosphere System

Published Online: 06 Sep 2013
Page range: 653 - 670

Abstract

Abstract

The process of stress accumulation near earthquake faults during the aseismic period in between two major seismic events in seismically active regions has become a subject of research during the last few decades. In the present paper a long dip -slip fault is taken to be situated in a viscoelastic layer over a viscoelastic half space representing the lithosphere-asthenosphere system. A movement of the dip-slip nature across the fault occurs when the accumulated stress due to various tectonic reasons, e.g., mantle convection etc., exceeds the local friction and cohesive forces across the fault. The movement is assumed to be slipping in nature, expressions for displacements, stresses and strains are obtained by solving the associated boundary value problem with the help of integral transformation and Green's function method. A detailed study of these expressions may give some ideas about the nature of stress accumulation in the system, which in turn will be helpful in formulating an earthquake prediction programme

Keywords

  • aseismic period
  • dip-slip fault
  • earthquake prediction
  • stress accumulation
  • viscoelastic-layered model
Open Access

Reflection of Waves in Initially Stressed Transversely Isotropic Fibre-Reinforced Thermoelastic Medium

Published Online: 06 Sep 2013
Page range: 671 - 685

Abstract

Abstract

The present investigation deals with the reflection of plane periodic waves incident at the surface of a homogeneous initially stressed transversely isotropic fibrereinforced thermoelastic medium. The wave equations are solved by imposing proper conditions on displacements, stresses and temperature distribution. Numerically simulated results have been depicted graphically for different angles of incidence with respect to frequency. Some special cases of interest have also been deduced from the present investigation

Keywords

  • reflection
  • initially stressed
  • fiber-reinforced
  • transversely isotropic
Open Access

A Concept of the Differentially Driven Three Wheeled Robot

Published Online: 06 Sep 2013
Page range: 687 - 698

Abstract

Abstract

The paper deals with the concept of a differentially driven three wheeled robot. The main task for the robot is to follow the navigation black line on white ground. The robot also contains anti-collision sensors for avoiding obstacles on track. Students learn how to deal with signals from sensors and how to control DC motors. Students work with the controller and develop the locomotion algorithm and can attend a competition

Keywords

  • robot
  • education
  • wheeled locomotion
  • sensor
  • mechatronics
Open Access

Unsteady Two-Layered Fluid Flow and Heat Transfer of Conducting Fluids in a Channel Between Parallel Porous Plates Under Transverse Magnetic Field

Published Online: 06 Sep 2013
Page range: 699 - 726

Abstract

Abstract

The unsteady magnetohydrodynamic flow of two immiscible fluids in a horizontal channel bounded by two parallel porous isothermal plates in the presence of an applied magnetic and electric field is investigated. The flow is driven by a constant uniform pressure gradient in the channel bounded by two parallel insulating plates, one being stationary and the other oscillating, when both fluids are considered as electrically conducting. Also, both fluids are assumed to be incompressible with variable properties, viz. different viscosities, thermal and electrical conductivities. The transport properties of the two fluids are taken to be constant and the bounding plates are maintained at constant and equal temperatures. The governing equations are partial in nature, which are then reduced to the ordinary linear differential equations using two-term series. Closed form solutions for velocity and temperature distributions are obtained in both fluid regions of the channel. Profiles of these solutions are plotted to discuss the effect on the flow and heat transfer characteristics, and their dependence on the governing parameters involved, such as the Hartmann number, porous parameter, ratios of the viscosities, heights, electrical and thermal conductivities

Keywords

  • magnetohydrodynamics
  • two-layered fluid flow/immiscible fluids
  • unsteady flow
  • oscillatory motion
  • heat transfer
  • porous plates
Open Access

Chemical Reaction Effects on MHD Flow Past a Linearly Accelerated Vertical Plate with Variable Temperature and Mass Diffusion in the Presence of Thermal Radiation

Published Online: 06 Sep 2013
Page range: 727 - 737

Abstract

Abstract

An exact solution of first order chemical reaction effects on a radiative flow past a linearly accelerated infinite isothermal vertical plate with variable mass diffusion, under the action of a transversely applied magnetic field has been presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C'w linearly with time. The dimensionless governing equations are tackled using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the magnetic field parameter, radiation parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that velocity increases with decreasing magnetic field parameter or radiation parameter. But the trend is just reversed with respect to the chemical reaction parameter

Keywords

  • accelerated
  • isothermal
  • radiation
  • vertical plate
  • heat and mass transfer
  • magnetic field
  • chemical reaction
Open Access

Heat Transfer of Viscoelastic Fluid Flow due to Nonlinear Stretching Sheet with Internal Heat Source

Published Online: 06 Sep 2013
Page range: 739 - 760

Abstract

Abstract

In the present paper, a viscoelastic boundary layer flow and heat transfer over an exponentially stretching continuous sheet in the presence of a heat source/sink has been examined. Loss of energy due to viscous dissipation of the non-Newtonian fluid has been taken into account in this study. Approximate analytical local similar solutions of the highly non-linear momentum equation are obtained for velocity distribution by transforming the equation into Riccati-type and then solving this sequentially. Accuracy of the zero-order analytical solutions for the stream function and velocity are verified by numerical solutions obtained by employing the Runge-Kutta fourth order method involving shooting. Similarity solutions of the temperature equation for non-isothermal boundary conditions are obtained in the form of confluent hypergeometric functions. The effect of various physical parameters on the local skin-friction coefficient and heat transfer characteristics are discussed in detail. It is seen that the rate of heat transfer from the stretching sheet to the fluid can be controlled by suitably choosing the values of the Prandtl number Pr and local Eckert number E, local viscioelastic parameter k*1 and local heat source/ sink parameter β*

Keywords

  • viscoelastic fluid
  • boundary layer flow
  • exponential stretching sheet
  • heat source/sink
  • heat transfer and skin friction
Open Access

Numerical Solution of Non-Newtonian Fluids Flow Past an Accelerated Vertical Infinite Plate in the Presence of Free Convection Currents

Published Online: 06 Sep 2013
Page range: 761 - 777

Abstract

Abstract

A similarity analysis of non-Newtonian fluid flow past an accelerated vertical infinite plate in the presence of free convection current is carried out. A group theoretic generalized dimensional analysis is employed to achieve the governing non-linear ordinary differential equations in the most general form. Numerical solutions of these equations are given with the plot of their velocity profiles with the effects of Pr-Prandtl number and Gr-Grashof number

Keywords

  • non-Newtonian fluids
  • convection currents
  • similarity analysis
Open Access

Flow and Heat Transfer at a Nonlinearly Shrinking Porous Sheet:The Case of Asymptotically Large Powerlaw Shrinking Rates

Published Online: 06 Sep 2013
Page range: 779 - 791

Abstract

Abstract

The boundary layer flow and heat transfer of a viscous fluid over a nonlinear permeable shrinking sheet in a thermally stratified environment is considered. The sheet is assumed to shrink in its own plane with an arbitrary power-law velocity proportional to the distance from the stagnation point. The governing differential equations are first transformed into ordinary differential equations by introducing a new similarity transformation. This is different from the transform commonly used in the literature in that it permits numerical solutions even for asymptotically large values of the power-law index, m. The coupled non-linear boundary value problem is solved numerically by an implicit finite difference scheme known as the Keller- Box method. Numerical computations are performed for a wide variety of power-law parameters (1 < m < 100,000) so as to capture the effects of the thermally stratified environment on the velocity and temperature fields. The numerical solutions are presented through a number of graphs and tables. Numerical results for the skin-friction coefficient and the Nusselt number are tabulated for various values of the pertinent parameters.

Keywords

  • boundary layer flow
  • porous shrinking sheet
  • Keller-Box method
  • similarity solutions
  • heat transfer
Open Access

Response of Non-Linear Shock Absorbers-Boundary Value Problem Analysis

Published Online: 06 Sep 2013
Page range: 793 - 814

Abstract

Abstract

A nonlinear boundary value problem of two degrees-of-freedom (DOF) untuned vibration damper systems using nonlinear springs and dampers has been numerically studied. As far as untuned damper is concerned, sixteen different combinations of linear and nonlinear springs and dampers have been comprehensively analyzed taking into account transient terms. For different cases, a comparative study is made for response versus time for different spring and damper types at three important frequency ratios: one at r = 1, one at r > 1 and one at r <1. The response of the system is changed because of the spring and damper nonlinearities; the change is different for different cases. Accordingly, an initially stable absorber may become unstable with time and vice versa. The analysis also shows that higher nonlinearity terms make the system more unstable. Numerical simulation includes transient vibrations. Although problems are much more complicated compared to those for a tuned absorber, a comparison of the results generated by the present numerical scheme with the exact one shows quite a reasonable agreement

Keywords

  • shock absorber
  • untuned vibration damper
  • frequency ratios
  • non-linear springs
  • non-linear dampers
  • stability
  • boundary value problem
  • multisegment method of integration
Open Access

Interactions due to Moving Heat Sources in Generalized Thermoelastic Half-Space using L-S Model

Published Online: 06 Sep 2013
Page range: 815 - 831

Abstract

Abstract

A one-dimensional problem for a homogeneous, isotropic and thermoelastic half-space subjected to a moving plane of heat source on the boundary of the space, which is traction free, is considered in the context of Lord- Shulaman model (L-S model) of thermoelasticity. The Laplace transform and eigenvalue approach techniques are used to solve the resulting non-dimensional coupled equations. Numerical results for the temperature, thermal stress, and displacement distributions are represented graphically and discussed

Keywords

  • generalized thrmoelasticity
  • L-S model
  • elastic half-space
  • moving heat sources
  • eigenvalue approach
Open Access

Effects of Chemical Reaction on Magneto-Micropolar Fluid Flow from a Radiative Surface with Variable Permeability

Published Online: 06 Sep 2013
Page range: 833 - 851

Abstract

Abstract

This paper presents a study of a hydromagnetic free convection flow of an electrically conducting micropolar fluid past a vertical plate through a porous medium with a heat source, taking into account the homogeneous chemical reaction of first order. A uniform magnetic field has also been considered in the study which acts perpendicular to the porous surface of the above plate. The analysis has been done by assuming varying permeability of the medium and the Rosseland approximation has been used to describe the radiative heat flux in the energy equation. Numerical results are presented graphically in the form of velocity, micro- rotation, concentration and temperature profiles, the skin-friction coefficient, the couple stress coefficient, the rate of heat and mass transfers at the wall for different material parameters. The study clearly demonstrates how a chemical reaction influences the above parameters under given conditions

Keywords

  • chemical reaction
  • micro-polar fluid
  • micro-rotation
  • magneto-hydrodynamics
  • heat and mass transfer
Open Access

Exact Solution Of MHD Mixed Convection Periodic Flow In A Rotating Vertical Channel With Heat Radiation

Published Online: 06 Sep 2013
Page range: 853 - 869

Abstract

Abstract

Magnetohydrodynamic (MHD) mixed convection flow of a viscous, incompressible and electrically conducting fluid in a vertical channel is analyzed analytically. A magnetic field of uniform strength is applied perpendicular to the planes of the channel walls. The fluid is acted upon by a periodic variation of the pressure gradient in the vertically upward direction. The temperature of one of the plates is non-uniform and the temperature difference of the walls of the channel is high enough to induce heat transfer due to radiation. The fluid and the channel rotate in unison with an angular velocity about the axis normal to the plates of the channel. An exact analytical solution of the problem is obtained. Two cases of small and large rotation have been considered to assess the effects of different parameters involved in the flow problem. The velocity field, the amplitude and the phase angle of the shear stress are shown graphically and discussed in detail. During analysis it is found that the flow problem studied by Makinde and Mhone (2005) is incorrect physically and mathematically

Keywords

  • periodic flow
  • mixed convection
  • magnetohydrodynamic (MHD)
  • rotating system
  • heat radiation
Open Access

Hall Effect on Thermal Instability of Viscoelastic Dusty Fluid in Porous Medium

Published Online: 06 Sep 2013
Page range: 871 - 886

Abstract

Abstract

The effect of Hall currents and suspended dusty particles on the hydromagnetic stability of a compressible, electrically conducting Rivlin-Ericksen elastico viscous fluid in a porous medium is considered. Following the linearized stability theory and normal mode analysis the dispersion relation is obtained. For the case of stationary convection, Hall currents and suspended particles are found to have destabilizing effects whereas compressibility and magnetic field have stabilizing effects on the system. The medium permeability, however, has stabilizing and destabilizing effects on thermal instability in contrast to its destabilizing effect in the absence of the magnetic field. The critical Rayleigh numbers and the wave numbers of the associated disturbances for the onset of instability as stationary convection are obtained and the behavior of various parameters on critical thermal Rayleigh numbers are depicted graphically. The magnetic field, Hall currents and viscoelasticity parameter are found to introduce oscillatory modes in the systems, which did not exist in the absence of these parameters

Keywords

  • thermal instability
  • Rivlin-Ericksen viscoelastic fluid
  • suspended particles
  • Hall current effect
  • porous medium
Open Access

Static, Vibration and Buckling Analysis of Skew Composite and Sandwich Plates Under Thermo Mechanical Loading

Published Online: 06 Sep 2013
Page range: 887 - 898

Abstract

Abstract

Static, vibration and buckling behavior of laminated composite and sandwich skew plates is studied using an efficient C0 FE model developed based on refined higher order zigzag theory. The C0 FE model satisfies the interlaminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model, the first derivatives of transverse displacement have been treated as independent variables to overcome the problem of C1 continuity associated with the plate theory. The C0 continuity of the present element is compensated in the stiffness matrix formulation by adding a suitable term. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature is made consistent with the total strain field by using field consistent approach. Numerical results are presented for different static, vibration and buckling problems by applying the FE model under thermo mechanical loading, where a nine noded C0 continuous isoparametric element is used. It is observed that there are very few results available in the literature on laminated composite and sandwich skew plates based on refined theories. As such many new results are also generated for future reference

Keywords

  • skew plate
  • finite element
  • refined theory
  • thermal load
Open Access

Effect of Vertical Vibrations on the Onset of Binary Convection

Published Online: 06 Sep 2013
Page range: 899 - 910

Abstract

Abstract

In the present work the linear stability analysis of double diffusive convection in a binary fluid layer is performed. The major intention of this study is to investigate the influence of time-periodic vertical vibrations on the onset threshold. A regular perturbation method is used to compute the critical Rayleigh number and wave number. A closed form expression for the shift in the critical Rayleigh number is calculated as a function of frequency of modulation, the solute Rayleigh number, Lewis number, and Prandtl number. These parameters are found to have a significant influence on the onset criterion; therefore the effective control of convection is achieved by proper tuning of these parameters. Vertical vibrations are found to enhance the stability of a binary fluid layer heated and salted from below. The results of this study are useful in the areas of crystal growth in micro-gravity conditions and also in material processing industries where vertical vibrations are involved

Keywords

  • gravity modulation
  • g-jitter
  • double diffusive convection
  • perturbation method
Open Access

Probabilistic Study of Bone Remodeling Using Finite Element Analysis

Published Online: 06 Sep 2013
Page range: 911 - 921

Abstract

Abstract

The dynamic bone remodeling process is a computationally challenging research area that struggles to understand the actual mechanisms. It has been observed that a mechanical stimulus in the bone greatly affects the remodeling process. A 3D finite element model of a femur is created and a probabilistic analysis is performed on the model. The probabilistic analysis measures the sensitivities of various parameters related to the material properties, geometric properties, and the three load cases defined as Single Leg Stance, Abduction, and Adduction. The sensitivity of each parameter is based on the calculated maximum mechanical stimulus and analyzed at various values of probabilities ranging from 0.001 to 0.999. The analysis showed that the parameters associated with the Single Leg Stance load case had the highest sensitivity with a probability of 0.99 and the angle of the force applied to the joint of the proximal femur had the overall highest sensitivity

Keywords

  • probabilistic analysis
  • bone remodeling
  • finite element analysis
Open Access

Identification of Steady and Non-Steady Gait of Humanexoskeleton Walking System

Published Online: 06 Sep 2013
Page range: 923 - 933

Abstract

Abstract

In this paper a method of analysis of exoskeleton multistep locomotion was presented by using a computer with the preinstalled DChC program. The paper also presents a way to analytically calculate the “,motion indicator”, as well as the algorithm calculating its two derivatives. The algorithm developed by the author processes data collected from the investigation and then a program presents the obtained final results. Research into steady and non-steady multistep locomotion can be used to design two-legged robots of DAR type and exoskeleton control system

Keywords

  • identification
  • steady gait
  • non-steady gait
  • exoskeleton
Open Access

Non-Perturbative Solution for Hydromagnetic Flow Over a Linearly Stretching Sheet

Published Online: 06 Sep 2013
Page range: 935 - 943

Abstract

Abstract

In this paper, the Adomian decomposition method with Padé approximants are integrated to study the boundary layer flow of a conducting fluid past a linearly stretching sheet under the action of a transversely imposed magnetic field. A closed form power series solution based on Adomian polynomials is obtained for the similarity nonlinear ordinary differential equation modelling the problem. In order to satisfy the farfield condition, the Adomian power series is converted to diagonal Padé approximants and evaluated. The results obtained using ADM-Padé are remarkably accurate compared with the numerical results. The proposed technique can be easily employed to solve a wide range of nonlinear boundary value problems

Keywords

  • stretching sheet
  • hydromagnetic flow
  • ADM-Padé
  • numerical solution
Open Access

Mass Transfer with Chemical Reaction on Flow Past an Accelerated Vertical Plate with Variable Temperature and Thermal Radiation

Published Online: 06 Sep 2013
Page range: 945 - 953

Abstract

Abstract

An exact solution of an unsteady radiative flow past a uniformly accelerated infinite vertical plate with variable temperature and mass diffusion is presented here, taking into account the homogeneous chemical reaction of first order. The plate temperature as well as concentration near the plate is raised linearly with time. The dimensionless governing equations are solved using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number, radiation parameter, chemical reaction parameter and time. It is observed that the velocity increases with increasing values of the thermal Grashof number or mass Grashof number. But the trend is just reversed with respect to the thermal radiation parameter. It is also observed that the velocity increases with the decreasing chemical reaction parameter

Keywords

  • linearly accelerated
  • chemical reaction
  • radiation
  • heat and mass transfer
Open Access

A New Analytical Procedure for Solving the Non-Linear Differential Equation Arising in the Stretching Sheet Problem

Published Online: 06 Sep 2013
Page range: 955 - 964

Abstract

Abstract

The paper discusses a new analytical procedure for solving the non-linear boundary layer equation arising in a linear stretching sheet problem involving a Newtonian/non-Newtonian liquid. On using a technique akin to perturbation the problem gives rise to a system of non-linear governing differential equations that are solved exactly. An analytical expression is obtained for the stream function and velocity as a function of the stretching parameters. The Clairaut equation is obtained on consideration of consistency and its solution is shown to be that of the stretching sheet boundary layer equation. The present study throws light on the analytical solution of a class of boundary layer equations arising in the stretching sheet problem

Keywords

  • differential equations
  • Clairaut equation
  • Newtonian liquid
  • stretching sheet
  • suction/injection
Open Access

Projective Synchronization of Chaotic Systems Via Backstepping Design

Published Online: 06 Sep 2013
Page range: 965 - 973

Abstract

Abstract

Chaos synchronization of discrete dynamical systems is investigated. An algorithm is proposed for projective synchronization of chaotic 2D Duffing map and chaotic Tinkerbell map. The control law was derived from the Lyapunov stability theory. Numerical simulation results are presented to verify the effectiveness of the proposed algorithm

Keywords

  • Lyapunov function
  • projective synchronization
  • backstepping
  • design

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