Manglayatan University

Alīgarh, India

Manglayatan University

Alīgarh, India

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Yadav D.,Indian Institute of Technology Roorkee | Bhargava R.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University | Yadav N.,Indian Institute of Technology Roorkee | And 2 more authors.
Microfluidics and Nanofluidics | Year: 2014

The stability of a non-Newtonian nanofluid saturated horizontal rotating porous layer subjected to thermal conductivity and viscosity variation is investigated using linear and nonlinear stability analyses. The model used for the non-Newtonian nanofluid includes the effects of Brownian motion and thermophoresis. The Darcy law for the non-Newtonian nanofluid of the Oldroyd type is used to model the momentum equation. The linear theory based on the normal mode method, and the criteria for both stationary and oscillatory modes are derived analytically. A weak nonlinear analysis based on the minimal representation of truncated Fourier series method containing only two terms is used to compute the concentration and thermal Nusselt numbers. The results obtained during the analysis are presented graphically. © Springer-Verlag Berlin Heidelberg 2013.


Awasthi M.K.,Graphic Era University | Yadav D.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University
Journal of Applied Fluid Mechanics | Year: 2014

A linear analysis of Rayleigh-Taylor instability in the presence of tangential electric field has been carried out using viscous potential flow theory. In viscous potential flow theory, viscosity is not zero but viscous term in the Navier-Stokes equation is zero as vorticity is zero. Viscosity enters through normal stress balance and tangential stresses are not considered in viscous flow theory. A dispersion relation has been obtained and stability criterion has been given in the terms of critical value of electric field. It has been observed that tangential electric field influences stability of the system. A comparison between the results obtained by viscous potential analysis and inviscid potential flow has been made and found that viscosity reduces the growth of instability.


Awasthi M.K.,University of Petroleum and Energy Studies | Asthana R.,Munjal University | Agrawal G.S.,Manglayatan University
International Journal of Heat and Mass Transfer | Year: 2014

We study the linear Kelvin-Helmholtz instability of the interface between two viscous and incompressible fluids, when the phases are enclosed between two horizontal cylindrical surfaces coaxial with the interface in presence of mass and heat transfer across the interface. Here we use an irrotational theory known as viscous correction for the viscous potential flow theory; in which the discontinuities in the irrotational tangential velocity and shear stress are eliminated in the global energy balance by taking viscous contributions to the irrotational pressure. Both asymmetric and axisymmetric disturbances have been studied and stability criterion is given in terms of a critical value of relative velocity. It has been shown that the irrotational viscous flow with viscous correction gives rise to exactly the same dispersion relation as obtained by the dissipation method in which the viscous effect is accounted for by evaluating viscous dissipation using the irrotational flow. It has been observed that heat and mass transfer has destabilizing effect while irrotational shearing stresses stabilize the system. © 2014 Elsevier Ltd. All rights reserved.


Yadav D.,Indian Institute of Technology Roorkee | Bhargava R.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University
International Journal of Thermal Sciences | Year: 2012

The effect of internal heat source on the onset of Darcy-Brinkman convection in a porous layer saturated by nanofluid is studied. The boundaries are considered to be free-free, rigid-rigid and lower-rigid and upper-free boundaries. The Brinkman-Darcy equation with fluid viscosity different from effective viscosity is used to characteristic the nanofluid motion. The model used for nanofluid includes the effects of Brownian motion and thermophoresis. The linear stability theory is employed and the resulting eigenvalue problem is solved numerically using the Galerkin technique with the Rayleigh number as the eigenvalue. The influence of internal heat source strength, nanoparticle Rayleigh number, modified particle-density increment, modified diffusivity ratio, Lewis number, Darcy number and the porosity on the stability of the system is investigated graphically. It is found that the internal heat source, nanoparticle Rayleigh number, modified diffusivity ratio and Lewis number have a destabilizing effect while Darcy number and the porosity show stabilizing effects on the system. © 2012 Elsevier Masson SAS. All rights reserved.


Tiwari D.K.,P.A. College | Awasthi M.K.,University of Petroleum and Energy Studies | Agrawal G.S.,Manglayatan University
Ain Shams Engineering Journal | Year: 2015

A linear analysis of capillary instability of a cylindrical interface in the presence of axial magnetic field has been carried out when there is heat and mass transfer across the interface. Both fluids are taken as incompressible, viscous and magnetic with different kinematic viscosities and different magnetic permeabilities. Viscous potential flow theory is used for the investigation and a dispersion relation that accounts for the growth of axisymmetric waves is derived. Stability criterion is given by critical value of applied magnetic field as well as critical wave number and stability is discussed theoretically as well as numerically. Various graphs are drawn showing the effect of various physical parameters such as magnetic field strength, heat transfer capillary number, and permeability ratio, on the stability of the system. It has been observed that the axial magnetic field and heat and mass transfer both have stabilizing effect on the stability of the system. © 2015 Faculty of Engineering, Ain Shams University.


Tiwari D.K.,P.A. College | Awasthi M.K.,University of Petroleum and Energy Studies | Agrawal G.S.,Manglayatan University
International Journal of Applied Electromagnetics and Mechanics | Year: 2015

We study the electrohydrodynamic capillary instability of the interface between two uniform superposed viscous and electrically conducting fluids in the presence of a free surface charge, when there is heat and mass transfer across the interface. The fluids are subjected to the uniform electric field in the axial direction and the viscous potential flow theory is used for the investigation. A quadratic dispersion relation that accounts for the growth of disturbance waves is derived for the linear stability analysis and the stability of the system is analyzed theoretically and numerically. The stability criterion is given in terms of the critical value of applied electric field as well as critical wave number. Various graphs with respect to physical parameters such as electric field, heat transfer coefficients, conductivity and permittivity ratio are drawn and effect of various parameters is described. It is observed that free surface charge and electric field both have stabilizing effect on the stability of the system. © 2015 - IOS Press and the authors. All rights reserved


Yadav D.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University | Bhargava R.,Indian Institute of Technology Roorkee
Journal of Porous Media | Year: 2013

The effects of thermal conductivity and viscosity variation on the onset of double-diffusive convection in a nanofluidsaturated porous layer heated and salted from below is studied using linear stability analysis. A two-component nonhomogeneous equilibrium model is used for the nanofluid that incorporates the effects of Brownian motion and thermophoresis. The resulting eigenvalue problem is solved using a Galerkin method that gives the criterion for both stationary and oscillatory convection. It has been observed that, the thermal conductivity and viscosity variation with nanoparticle volume fraction delay the onset of convection. © 2013 by Begell House, Inc.


Yadav D.,Indian Institute of Technology Roorkee | Bhargava R.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University
Journal of Engineering Mathematics | Year: 2013

The combined effect of a vertical magnetic field and the boundaries on the onset of convection in an electrically conducting nanofluid layer heated from below is investigated using linear stability theory. The employed model incorporates the effects of Brownian motion and thermophoresis. The boundaries are considered to be either rigid or free. The eigenvalue problem is solved analytically for free-free boundaries and numerically for rigid-rigid and lower-rigid and upper-free boundaries using the Galerkin technique. Numerical results are presented for alumina-water nanofluid. © 2013 Springer Science+Business Media Dordrecht.


Yadav D.,Indian Institute of Technology Roorkee | Bhargava R.,Indian Institute of Technology Roorkee | Agrawal G.S.,Manglayatan University
International Journal of Heat and Mass Transfer | Year: 2013

Thermal instability of a nanofluid layer heated from below in the presence of rotation is investigated. The lower boundary of the nanofluid layer is considered to be rigid, while the upper boundary is assumed to be either rigid or free. The effects of Brownian motion and thermophoresis have been included in the model of nanofluid. The 6-term Galerkin method is used to obtain the eigenvalue equation, which is then solved numerically. The effects of rotation and other physical parameters on the onset of convection are analyzed and compared for two types velocity boundary conditions considered. Besides, some known results available in the literature are compared with those obtained from the present study and good agreement is found. © 2013 Elsevier Ltd. All rights reserved.


Awasthi M.K.,University of Petroleum and Energy Studies | Asthana R.,Galgotias University | Agrawal G.S.,Manglayatan University
Scientia Iranica | Year: 2014

A linear analysis of the temporal instability of a viscoelastic liquid jet with axisymmetric and asymmetric disturbances moving in an infinite viscous fluid is investigated. The cause of the instability in the liquid jet is Kelvin-Helmholtz instability, due to the velocity difference and capillary instability, due to surface tension. The dispersion relation for viscoelastic potential flow is cubic in nature. The stability analysis shows that viscoelastic liquid jets are less unstable than inviscid jets and more unstable than viscous liquid jets for both axisymmetric and asymmetric disturbances. Stability analysis has been undertaken in terms of various parameters, such as Weber number, Reynolds number, Deborah number etc. © 2014 Sharif University of Technology. All rights reserved.

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