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Fotini Labropulu - One of the best experts on this subject based on the ideXlab platform.

  • Unsteady Stagnation-Point Flow of a Second-grade Fluid
    Journal of Fluid Flow Heat and Mass Transfer, 2016
    Co-Authors: Fotini Labropulu
    Abstract:

    The unsteady two-dimensional Stagnation Point Flow of second-grade fluid impinging on an infinite plate is examined and solutions are obtained. It is assumed that the infinite plate at ��= 0 is making harmonic oscillations in its own plane. Solutions for small and large frequencies of the oscillations are obtained for various values of the Weissenberg number. The effect of the Weissenberg number is to decrease the velocity near the wall as it increases.

  • Unsteady Oscillatory Stagnation Point Flow of a Jeffrey Fluid
    Journal of Aerospace Engineering, 2014
    Co-Authors: Sohail Nadeem, Fotini Labropulu, Bushra Tahir, Noreen Sher Akbar
    Abstract:

    AbstractIn the present paper, the unsteady oscillatory Stagnation Point Flow of a Jeffrey fluid is discussed. The oscillatory Stagnation Point Flows have been discussed in a fixed frame of reference and a moving frame of reference. The convergence of the obtained analytical solutions has been discussed by plotting ℏ-curves. Lastly, the physical significance of various parameters is discussed through graphs.

  • Two-dimensional oblique Stagnation-Point Flow towards a stretching surface in a viscoelastic fluid
    Open Physics, 2011
    Co-Authors: Iqbal Husain, Fotini Labropulu, Ioan Pop
    Abstract:

    In this paper, the steady two-dimensional Stagnation-Point Flow of a viscoelastic Walters’ B’ fluid over a stretching surface is examined. It is assumed that the fluid impinges on the wall obliquely. Using similarity variables, the governing partial differential equations are transformed into a set of two non-dimensional ordinary differential equations. These equations are then solved numerically using the shooting method with a finite-difference technique.

  • Oblique Stagnation-Point Flow of a viscoelastic fluid with heat transfer
    International Journal of Non-Linear Mechanics, 2009
    Co-Authors: Fotini Labropulu, Ioan Pop
    Abstract:

    Abstract The two-dimensional forced convection Stagnation-Point Flow and heat transfer of a viscoelastic second grade fluid obliquely impinging on an infinite plane wall is considered as an exact solution of the full partial differential equations. This oblique Flow consists of an orthogonal Stagnation-Point Flow to which a shear Flow whose vorticity is fixed at infinity is added. The relative importance of these Flows is measured by a parameter γ . The viscoelastic problem is reduced to two ordinary differential equations governed by the Weissenberg number W e , two parameters α  and β , the later being a free parameter β , introduced by Tooke and Blyth [A note on oblique Stagnation-Point Flow, Physics of Fluids 20 (2008) 033101-1–3], and the Prandtl number Pr . The two cases when α = β  and α ≠ β  are, respectively, considered. Physically the free parameter may be viewed as altering the structure of the shear Flow component by varying the magnitude of the pressure gradient. It is found that the location of the separation Point x s  of the boundary layer moves continuously from the left to the right of the origin of the axes ( x s 0 ).

  • Stagnation-Point Flow of a second-grade fluid with slip
    International Journal of Non-Linear Mechanics, 2008
    Co-Authors: Fotini Labropulu
    Abstract:

    Abstract The steady two-dimensional Stagnation-Point Flow of a second-grade fluid with slip is examined. The fluid impinges on the wall either orthogonally or obliquely. Numerical solutions are obtained using a quasi-linearization technique.

Tasawar Hayat - One of the best experts on this subject based on the ideXlab platform.

  • Double stratified Stagnation-Point Flow of Williamson nanomaterial with entropy generation through a porous medium
    International Journal of Numerical Methods for Heat & Fluid Flow, 2019
    Co-Authors: Muhammad Ijaz Khan, Tasawar Hayat, M.z. Kiyani, Muhammad Faisal Javed, I. Ahmad
    Abstract:

    This paper aims to address double-stratified Stagnation-Point Flow of Williamson nanomaterial with entropy generation. Flow through porous medium is discussed. Energy equation is modeled in existence of viscous dissipation, Brownian motion and thermophoresis. Furthermore, convective boundary conditions are considered. Total entropy rate is presented.,The non-linear Flow expressions are converted to ordinary ones by implementation of suitable transformations. The obtained ordinary system is tackled for series solutions via homotopy analysis method.,Till date no one has considered the irreversibility analysis in Stagnation-Point Flow of Williamson nanomaterial with double stratification, porous medium and convective conditions. The basic objective of present research is to investigate the convective Stagnation Point Flow of Williamson liquid with entropy concept and porous medium.,As per the authors’ knowledge, no such work is yet present in the literature.

  • newtonian heating in Stagnation Point Flow of burgers fluid
    Applied Mathematics and Mechanics-english Edition, 2015
    Co-Authors: Muhammad Awais, Tasawar Hayat, Shafqat Ali, M S Alhuthali
    Abstract:

    The Newtonian heating effects in the Stagnation Point Flow of a Burgers fluid are addressed in this paper. The boundary layer Flow problems are stated in the spatial domain from zero to infinity. The solution expressions for the velocity and the temperature are obtained and examined for the influential variables. The tabulated values show comparison with the previous results. It is observed that the obtained results are in good agreement with the existing results in limiting sense.

  • unsteady Stagnation Point Flow of second grade fluid with variable free stream
    alexandria engineering journal, 2014
    Co-Authors: Tasawar Hayat, S A Shehzad, Muhammad Qasim, Ahmed Alsaedi
    Abstract:

    Abstract This article discusses the Stagnation-Point Flow of second grade fluid over an unsteady stretching surface in the presence of variable free stream. Flow analysis has been carried out with heat transfer analysis. The resulting partial differential equations have been converted into ordinary differential equations by employing the suitable transformations. Computations of dimensionless velocity and temperature fields have been performed by using homotopy analysis method (HAM). Graphs are plotted to examine the behaviors of arising physical parameters on the dimensionless velocity and temperature. Numerical values of skin-friction coefficient and local Nusselt number are computed and examined.

  • Thermally Stratified Stagnation Point Flow of an Oldroyd-B Fluid
    International Journal of Nonlinear Sciences and Numerical Simulation, 2014
    Co-Authors: Tasawar Hayat, Zakir Hussain, Muhammad Farooq, Ahmed Alsaedi, Mustafa Obaid
    Abstract:

    This paper is devoted to examine the thermally stratified mixed convection Flow of an Oldroyd-B fluid. The Stagnation Point Flow towards a stretching surface is discussed. The boundary layer Flow and energy equations are employed. Resulting partial differential systems are converted into the ordinary differential systems. Convergent series solutions for velocity and temperature are developed and analyzed. Numerical values of Nusselt number is computed and examined. Comparison of present study is shown with the previous results. It is found that velocity decreases through the stratified effects.

  • melting heat transfer in the Stagnation Point Flow of powell eyring fluid
    Journal of Thermophysics and Heat Transfer, 2013
    Co-Authors: Tasawar Hayat, Muhammad Farooq, Ahmed Alsaedi, Z Iqbal
    Abstract:

    This paper looks at the influence of melting heat transfer in Stagnation Point Flow of Powell–Eyring fluid toward a linear stretching sheet. The mathematical modeling is characterized by conservation laws of mass, linear momentum, and energy. Appropriate similarity transformations are employed for the reduction of partial differential systems into the ordinary differential systems. Series solutions to the resulting problems are presented. Variations of embedded parameters into the derived problems are graphically illustrated. The skin-friction coefficient and the Nusselt number are computed and examined.

Ioan Pop - One of the best experts on this subject based on the ideXlab platform.

  • MHD mixed convection oblique Stagnation-Point Flow on a vertical plate
    International Journal of Numerical Methods for Heat & Fluid Flow, 2017
    Co-Authors: Giulia Giantesio, Anna Verna, Natalia C. Roşca, Alin V. Roşca, Ioan Pop
    Abstract:

    Purpose This paper aims to study the problem of the steady plane oblique Stagnation-Point Flow of an electrically conducting Newtonian fluid impinging on a heated vertical sheet. The temperature of the plate varies linearly with the distance from the Stagnation Point. Design/methodology/approach The governing boundary layer equations are transformed into a system of ordinary differential equations using the similarity transformations. The system is then solved numerically using the “bvp4c” function in MATLAB. Findings An exact similarity solution of the magnetohydrodynamic (MHD) Navier–Stokes equations under the Boussinesq approximation is obtained. Numerical solutions of the relevant functions and the structure of the Flow field are presented and discussed for several values of the parameters which influence the motion: the Hartmann number, the parameter describing the oblique part of the motion, the Prandtl number (Pr) and the Richardson numbers. Dual solutions exist for several values of the parameters. Originality value The present results are original and new for the problem of MHD mixed convection oblique Stagnation-Point Flow of a Newtonian fluid over a vertical flat plate, with the effect of induced magnetic field and temperature.

  • Unsteady MHD rear Stagnation-Point Flow over off-centred deformable surfaces
    International Journal of Numerical Methods for Heat & Fluid Flow, 2017
    Co-Authors: Mustafa Turkyilmazoglu, Kohilavani Naganthran, Ioan Pop
    Abstract:

    Purpose The purpose of this paper is to present both an analytical and a numerical analysis of the unsteady magnetohydrodynamic (MHD) rear Stagnation-Point Flow over off-centred deformable surfaces. Design/methodology/approach The numerical MATLAB solver bvp4c suitable for routine boundary value problem is used for the set of ordinary differential equations reduced from the governing partial differential equations. Findings Multiple solutions are found for particular eigenvalues. The physical solution is computed by the help of a linear stability analysis. The authors have succeeded in discovering the second solutions, and it is suggested that these solutions are unstable and not physically realisable in practice. The current findings add to a growing body of literature on MHD Stagnation-Point Flow problems. It is also found that the governing parameters have different effects on the Flow characteristics. Practical implications Even though problems of steady MHD Flows have been extensively studied for Stagnation-Point Flows, limited findings can be found on the unsteady MHD rear Stagnation-Point Flow over off-centred deformable surfaces. Originality/value The originality of this work is the application of a magnetic field on a time-dependent MHD rear Stagnation-Point Flow over off-centred deformable surfaces.

  • Unsteady separated Stagnation-Point Flow with suction towards a stretching sheet
    2014
    Co-Authors: Lok Yian Yian, Syakila Ahmad, Ioan Pop
    Abstract:

    The problem of unsteady boundary layer separated Stagnation-Point Flow towards a porous stretching sheet is considered. By using a similarity transformation, the governing equations are reduced to a system of ordinary differential equations which are then solved numerically. The effects of suction and stretching parameters on the Flow characteristics are studied. It is observed that the solutions admit two types of solutions, one is the attached Flow solution and the other is reverse Flow solution.

  • MHD Stagnation Point Flow with suction towards a shrinking sheet
    Sains Malaysiana, 2011
    Co-Authors: Lok Yian Yian, Anuar Mohd Ishak, Ioan Pop
    Abstract:

    A steady two-dimensional magnetohydrodynamic (MHD) Stagnation-Point Flow of a viscous and electrically conducting fluid over a permeable shrinking sheet has been studied. The governing partial differential equations are reduced to the nonlinear ordinary differential equations by a similarity transformation. The resulting differential equations are then solved numerically using an implicit finite difference method. It is found that the solutions are non-unique for weak magnetic field, strong suction and large velocity ratio between free stream velocity and wall shrinking velocity.

  • Two-dimensional oblique Stagnation-Point Flow towards a stretching surface in a viscoelastic fluid
    Open Physics, 2011
    Co-Authors: Iqbal Husain, Fotini Labropulu, Ioan Pop
    Abstract:

    In this paper, the steady two-dimensional Stagnation-Point Flow of a viscoelastic Walters’ B’ fluid over a stretching surface is examined. It is assumed that the fluid impinges on the wall obliquely. Using similarity variables, the governing partial differential equations are transformed into a set of two non-dimensional ordinary differential equations. These equations are then solved numerically using the shooting method with a finite-difference technique.

A S Gupta - One of the best experts on this subject based on the ideXlab platform.

  • Dual Solution of MHD Stagnation-Point Flow towards a Stretching Surface
    Engineering, 2010
    Co-Authors: Tapas Ray Mahapatra, Samir Kumar Nandy, A S Gupta
    Abstract:

    The effect of a uniform transverse magnetic field on two-dimensional Stagnation-Point Flow of an incompressible viscous electrically conducting fluid over a stretching surface is investigated when the surface is stretched in its own plane with a velocity proportional to the distance from the Stagnation-Point. This magnetohydrodynamic (MHD) Flow problem is governed by the parameter b representing the ratio of the strain rate of the Stagnation-Point Flow to that of the stretching sheet and the magnetic field parameter M. It is known from a previous paper [9] that if b > 1, the steady solution to the problem is monotonic increasing and the solution is also unique. But when 0 0.23919, the non-monotonic solution cannot exist and so in this case, the only solution is monotonic decreasing. A stability analysis reveals that when 0 < b < bc, the solutions along the upper branch corresponding to the monotonic solution are linearly stable while those along the lower branch for the non-monotonic solution are linearly unstable. It is also shown that the decay rate of a disturbance increases with increasing M for the stable solution but the growth rate of instability for the non-monotonic solution decreases with increasing M.

  • Stagnation Point Flow towards a stretching surface
    Canadian Journal of Chemical Engineering, 2008
    Co-Authors: Tapas Ray Mahapatra, A S Gupta
    Abstract:

    An exact similarity solution of the Navier-Stokes equations is obtained. The solution represents steady axisymmetric Stagnation-Point Flow towards a stretching surface. It is shown that the Flow displays a boundary-layer structure when the stretching velocity of the surface is less than the free stream velocity. On the other hand, an inverted boundary layer is formed when the surface stretching velocity exceeds the free stream velocity. Temperature distribution in the Flow is found when the surface is held at a constant temperature. It turns out that when the surface temperature exceeds the ambient temperature, heat Flows from the surface to the fluid near the Stagnation Point but further away from the Stagnation Point, heat Flows from the fluid to the stretching surface.

  • Stagnation‐Point Flow towards a Stretching Surface
    The Canadian Journal of Chemical Engineering, 2008
    Co-Authors: Tapas Ray Mahapatra, A S Gupta
    Abstract:

    An exact similarity solution of the Navier-Stokes equations is obtained. The solution represents steady axisymmetric Stagnation-Point Flow towards a stretching surface. It is shown that the Flow displays a boundary-layer structure when the stretching velocity of the surface is less than the free stream velocity. On the other hand, an inverted boundary layer is formed when the surface stretching velocity exceeds the free stream velocity. Temperature distribution in the Flow is found when the surface is held at a constant temperature. It turns out that when the surface temperature exceeds the ambient temperature, heat Flows from the surface to the fluid near the Stagnation Point but further away from the Stagnation Point, heat Flows from the fluid to the stretching surface.

  • Stagnation Point Flow of a viscoelastic fluid towards a stretching surface
    International Journal of Non-linear Mechanics, 2004
    Co-Authors: Ray T Mahapatra, A S Gupta
    Abstract:

    Abstract An analysis is made of the steady two-dimensional Stagnation-Point Flow of an incompressible viscoelastic fluid over a flat deformable surface when the surface is stretched in its own plane with a velocity proportional to the distance from the Stagnation-Point. It is shown that for a viscoelastic fluid of short memory (obeying Walters’ B′ model), a boundary layer is formed when the stretching velocity of the surface is less than the inviscid free-stream velocity and velocity at a Point increases with increase in the elasticity of the fluid. On the other hand, an inverted boundary layer is formed when the surface stretching velocity exceeds the velocity of the free stream and the velocity decreases with increase in the elasticity of the fluid. A novel result of the analysis is that the Flow near the stretching surface is that corresponding to an inviscid Stagnation-Point Flow when the surface stretching velocity is equal to the velocity of the free stream. Temperature distribution in the boundary layer is found when the surface is held at constant temperature and surface heat flux is determined. It is found that temperature at a Point decreases with increase in the elasticity of the fluid.

  • heat transfer in Stagnation Point Flow towards a stretching sheet
    Heat and Mass Transfer, 2002
    Co-Authors: Ray T Mahapatra, A S Gupta
    Abstract:

    Steady two-dimensional Stagnation-Point Flow of an incompressible viscous fluid over a flat deformable sheet is investigated when the sheet is stretched in its own plane with a velocity proportional to the distance from the Stagnation-Point. It is shown that for a fluid of small kinematic viscosity, a boundary layer is formed when the stretching velocity is less than the free stream velocity and an inverted boundary layer is formed when the stretching velocity exceeds the free stream velocity. Temperature distribution in the boundary layer is found when the surface is held at constant temperature and surface heat flux is determined.

M. Chinichian - One of the best experts on this subject based on the ideXlab platform.