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1
Content available Variable thermal conductivity and mass diffusivity effects in a free convective flow of doubly stratified non-darcian porous medium over a vertical plate
Suganthi R. K., Pullepu Babuji, Supriya P., Shanmugapriya M., Pop I.
International Journal of Applied Mechanics and Engineering
|
2024
|
Vol. 29, no. 1
159--178
EN
The research in this article is carried out to study incompressible and unsteady free convective flow on a semi-infinite isothermal vertical plate in a doubly stratified non-Darcian porous media with variable mass diffusivity and variable thermal conductivity. The governing non-linear partial differential equations of flow were calculated by applying an implicit finite difference scheme of Crank-Nicolson type. Various parametric impacts on concentration profiles, temperature, velocity, as well Sherwood number, Nusselt number and skin friction, were examined and presented in graphs. It is examined that there exists a significant temperature decrease for high Darcy number in stratified fluids. Also, it is detected that the presence of stratification produces a considerable drop in skin friction while increases the mass and heat transfer rate. Comparison of current outcomes well agreed with the available solutions.
2
Content available remote Movability and Uniform Movability of Shape Morphisms
Gevorgyan P. S., Pop I.
Bulletin of the Polish Academy of Sciences. Mathematics
|
2016
|
Vol. 64, no. 1
69--83
EN
The purpose of this paper is to define some notions of movability for morphisms of inverse systems which extend the movability properties of inverse systems and which are compatible with the equivalence relations which define pro-morphisms and shape morphisms. Some properties and applications are given.
3
Content available Flow and heat transfer at a nonlinearly shrinking porous sheet: the case of asymptotically large powerlaw shrinking rates
Prasad K. V., Vajravelu K., Pop I.
International Journal of Applied Mechanics and Engineering
|
2013
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Vol. 18, no. 3
779--791
EN
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.
4
Content available remote Mixed convection boundary layer flow about a solid sphere with Newtonian heating
Salleh M. Z., Nazar R., Pop I.
Archives of Mechanics
|
2010
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Vol. 62, nr 4
283-303
EN
In this paper, the steady mixed convection boundary layer flow about a solid sphere, generated by Newtonian heating in which the heat transfer from the surface is proportional to the local surface temperature, is considered. The governing boundary layer equations are first transformed into a system of non-dimensional equations via the non-dimensional variables, and then into non-similar equations before they are solved numerically, using an implicit finite-difference scheme known as the Keller-box method. Numerical solutions are obtained for the skin friction coefficient and the wall temperature, as well as the velocity and temperature profiles with several parameters considered, namely the mixed convection parameter lambda, the Prandtl number Pr and the conjugate parameter gamma.
5
Content available remote Unsteady free convection flow along a vertical cone in a stable thermally stratified medium
Bapuji P., Ekambavanan K., Pop I.
International Journal of Applied Mechanics and Engineering
|
2009
|
Vol. 14, no 4
1073-1092
EN
Unsteady natural convection flow of a viscous and incompressible fluid flow over a vertical cone immersed in a stable thermally stratified medium is theoretically studied in this paper. The dimensionless coupled partial differential boundary layer equations are solved numerically using an efficient and unconditionally stable finite-difference scheme of Crank-Nicolson type. The effects of the Prandtl number and stratification parameter on the velocity and temperature profiles as well as the local and average skin friction and Nusselt numbers on the flow and heat transfer characteristics have been determined and discussed in detail. The present results are compared with available results from the open literature and are found to be in good agreement.
6
Content available remote Boundary layers growth on a moving surface due to an impulsive motion and a sudden increase of wall heat flux
Kumari M., Grosan T., Pop I.
International Journal of Applied Mechanics and Engineering
|
2008
|
Vol. 13, no 1
203-215
EN
In this paper we investigate the development of the momentum and thermal boundary layers over a continuous moving semi-infinite flat plate when the extemal stream starts impulsively from rest at time t = O with a constant velocity [...] It is assumed that the plate starts to supply heat to the fluid at a constant rate qw at time t = O and maintained at this rate. The problem has been formulated in a new system of scaled coordinates such that for [...] it reduces to Rayleigh type of equation and for [...] (large time) it reduces to Blasius or Sakiadis type of equation. A new scale of dimensionless time ? has been used which reduces the region of time integration from an infinite region [...] to a finite time region [...] which reduces the computational time considerably. The goveming partial differential equations are transformed into a singular parabolic partial differential equations which have been solved numerically for a range of values of the goveming parameters using an implicit finite-difference scheme. The results show that there is a smooth transition from Rayleigh solution to Blasius or Sakiadis solution as the dimensionless time [...] increases from zero to one.
7
Content available remote Post-stagnation-point boundary layer flow and mixed convection heat transfer over a vertical, linearly stretching sheet
Ishak A., Nazar R., Pop I.
Archives of Mechanics
|
2008
|
Vol. 60, nr 4
303-322
EN
A theoretical analysis is made for the steady two-dimensional post-stagnationpoint flow of an incompressible viscous fluid over a stretching vertical sheet in its own plane. The stretching velocity, the free stream velocity and the surface temperature are assumed to vary linearly with the distance from the stagnation point. The governing partial differential equations are transformed into a coupled system of ordinary differential equations, which is then solved numerically by a finite-difference method. Results are presented in terms of the skin friction coefficient and local Nusselt number, along with a selection of velocity and temperature profiles. It was shown that for both cases of a fixed surface (? = 0) and a stretching surface (? = 0), dual solutions exist for the assisting flow (positive values of the buoyancy parameter ?), besides that usually reported in the literature for the opposing flow (? < 0). It was also found that for the assisting flow, a solution exists for all values of ? (> 0), while for the opposing flow, a solution exists only if the magnitude of the buoyancy parameter is small.
8
Content available remote Unsteady free convection over a vertical plate subject to a step change of the surface temperature or heat flux in a stratified porous medium
Magyari E., Keller B., Pop I.
International Journal of Applied Mechanics and Engineering
|
2007
|
Vol. 12, no 2
465-476
EN
The problem of unsteady free convection heat transfer from a one-dimensional (parallel) flow along an infinite verticaI fiat plate embedded in a thermaIly stratified fluid-saturated porous medium is considered. FIows are induced by a step change in surface temperature or heat flux. By a formaI reduction of the corresponding boundary vaIue problems to well known Fourier heat conduction problems, analytical solutions of the Darcy and energy equations are obtained.
9
Content available remote Mixed convection along a vertical cone with uniform surface heat flux for fluids of any Prandtl number
Kumari M., Jaradat M. A., Pop I.
International Journal of Applied Mechanics and Engineering
|
2007
|
Vol. 12, no 3
733-744
EN
An analysis of a steady laminar mixed convection boundary layer flow along a vertical cone of constant wall heat flux for any Prandtl number is presented. A mixed convection parameter [...], as proposed by Lin and Chen (1988), is used to serve as a controlling parameter that determines the relative importance of the forced and the free convection flows. New coordinates and dependent variabIes are then defined in terms of [...], so that the transformed non-similar boundary layer equations give computationally efficient numerical solutions which are valid over the entire range of the mixed convection flow from the forced convection limit [...] to the free convection limit [...] for fluids of any Prandtl number. The effect of the mixed convection parameter and the Prandtl number on the velocity and temperature profile s as well as on the skin friction and heat transfer coefficients are shown for both cases of buoyancy assisting and buoyancy opposing flow conditions, respectively.
10
Content available remote Flow due to non-coaxial rotations of a permeable disk and a fluid at infinity through a porous medium
Guria M., Manna G., Jana R. N., Pop I.
International Journal of Applied Mechanics and Engineering
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2007
|
Vol. 12, no 4
965-974
EN
Au exact solution of the flow due to non-co-axial rotation of a porous disk and a fluid at infinity through porous medium is obtained. It is found that the thickness of the boundary layer decreases with increase in permeability of the porous medium. The heat transfer characteristic of the flow has also been studied on taking viscous dissipation into account. It is found that the rate of heat transfer at the disk increases with increase in either suction at the disk or the permeability of the medium.
11
Content available remote Flow and heat transfer of couple stress and viscous fluids in a vertical channel
Umavathi J. C., Liu I. C., Pop I.
International Journal of Applied Mechanics and Engineering
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2007
|
Vol. 12, no 2
537-555
EN
The problem of steady, laminar, fully developed flow and heat transfer of viscous and couple stress fluids in a vertical channel is investigated. The transport properties of the fluids in both the regions are assumed to be constant. The walls of the channel are considered to be isothermaI. The goveming momentum and energy equations are coupled and nonlinear due to the buoyancy effects. The basic equations are solved analytically using the regular perturbation method and numerically using the Runge-Kutta-GiII method. The results are represented graphically for different vaIues of the couple stress parameter, viscosity ratio, width ratio, coefficient of thermaI expansion ratio, density ratio, conductivity ratio, ratio of the Grashof number and Reynolds number and Eckert number on velocity and temperature distributions. In addition, results for the Nusselt number are computed for different values of the physical parameters and presented in a tabular form. It is found that the effect of the couple stress parameter is to promote the motion of the fluid.
12
Content available remote Uniformly movable categories and uniform movability of topological spaces
Gevorgyan P. S., Pop I.
Bulletin of the Polish Academy of Sciences. Mathematics
|
2007
|
Vol. 55, no 3
229-242
EN
A categorical generalization of the notion of movability from inverse systems and shape theory was given by the first author who defined the notion of movable category and used it to interpret the movability of topological spaces. In this paper the authors define the notion of uniformly movable category and prove that a topological space is uniformly movable in the sense of shape theory if and only if its comma category in the horaotopy category HTop over the subcategory HPol of polyhedra is uniformly movable. This is a weakened version of the categorical notion of uniform movability introduced by the second author.
13
Content available remote Steady and unsteady boundary layers due to a stretching vertical sheet in a porous medium using Darcy-Brinkman equation model
Ishak A., Nazar R., Pop I.
International Journal of Applied Mechanics and Engineering
|
2006
|
Vol. 11, no 3
623-637
EN
The present paper deals with the analysis of steady and unsteady boundary layer flow and heat transfer past a vertical stretching sheet in a viscous fluid-saturated porous medium by using the Darcy-Brinkman equation model. It is assumed that unsteadiness is caused by the impulsive stretching of the sheet and by sudden increase in the surface temperature. The problem is reduced to parabolic partial differential equations, which are solved numerically using the Keller-box method. The small time (initial unsteady flow) as well as the large time (final steady-state flow) solutions are also included in the analysis. It is shown that there is a smooth transition from the small time solution to large time solution, respectively.
14
Content available remote Similiarity solutions for the unsteady boundary layer flow and heat transfer due to a stretching sheet
Sharidan S., Mahmood T., Pop I.
International Journal of Applied Mechanics and Engineering
|
2006
|
Vol. 11, no 3
647-654
EN
A similarity analysis is presented to investigate the unsteady boundary layers over a stretching sheet for special distributions of the stretching velocity and surface temperature or surface heat flux. The governing unsteady boundary layer equations are reduced to ordinary differential equations with two parameters, the Prandtl number and the unsteadiness parameter. These equations are solved numerically for some values of the governing parameters using the Keller-box method. Some flow and heat transfer characteristics are determined and discussed in detail.
15
Content available remote An analytical approach to MHD plasma behavior of a rotating environment in the presence of an inclined magnetic field as compared to excitation frequency
Ghosh S. K., Pop I.
International Journal of Applied Mechanics and Engineering
|
2006
|
Vol. 11, no 4
845-856
EN
We have examined the MHD plasma behavior of a rotating environment in the presence of an inclined magnetic field with the positive direction of the axis of rotation. The interplay of a hydromagnetic force and Coriolis force exerts its influence of a dynamo mechanism with reference to the solar and terrestrial context when the Hall current is taken into account. It is stated that the electrical discharge of the solar corona in the presence of a traveling magnetic field experiences an irregular fluctuation at the resonant level to produce thermonuclear fusion reaction of the Sun with regard to excitation frequency. On the other hand, the thermonuclear fusion reaction of the Sun stops when the excitation frequency is switched off and the MHD plasma flow tends to an equilibrium position with regard to a neutral plasma stability parameter.
16
Content available remote A note on the effect of radiation on free convection over a vertical flat plate embedded in a non-newtonian fluid saturated porous medium
Grosan T., Pop I.
International Journal of Applied Mechanics and Engineering
|
2006
|
Vol. 11, no 3
715-722
EN
The effect of radiation on the free convection from a vertical plate embedded in a power-law fluid saturated porous media has been considered. Similarity equations have been obtained and solved numerically. It was found that there is an increase in the boundary layer thickness with an increase in the radiation parameter N and a decrease in the power-law index n was observed.
17
Content available remote Flow of a micropolar fluid on a continuous moving surface
Ishak A., Nazar R., Pop I.
Archives of Mechanics
|
2006
|
Vol. 58, nr 6
529-541
EN
The present paper deals with the analysis of steady boundary layer flow and heat transfer of a micropolar fluid on an isothermal continuously moving plane surface. It is assumed that the microinertia density is variable and not constant, as in many other published papers. Also, the viscous dissipation effect is taken into account. The basic partial differential equations are reduced to a system of nonlinear ordinary differential equations, which is solved numerically using the Keller-box method. Numerical results are obtained for the skin friction coefficient, local Nusselt number, as well as velocity, temperature and microrotation profiles. Results are shown in graphical form and the numerical values for the skin friction coefficient and local Nusselt number are given in the form of tables. The effects of material parameter K, Prandtl number Pr and Eckert number Ec on the flow and heat transfer characteristics are discussed.
18
Content available remote G-jitter induced free convection near a two-dimensional stagnation point in micropolar fluids
Sharidan S., Amin N., Pop I.
International Journal of Applied Mechanics and Engineering
|
2005
|
Vol. 10, no 2
311-328
EN
A numerical solution for the effect of a small but fluctuating gravitational field, characteristic of g-jitter, on the free convection boundary layer flow near the forward stagnation point of a two-dimensional symmetric body resulting from a step change in its surface temperature and immersed in a micropolar fluid is presented in this paper. Both the cases when the spin gradient on the wall is zero and non-zero are considered. The transformed non-similar boundary layer equations are solved numerically by a very efficient implicit finite-difference scheme known as the Keller-box method to investigate the effects on the skin friction and on the rate of heat transfer of variations in the forcing amplitude, a, forcing frequency, 'omega', and micropolar parameter, K. The results are given for a value of the Prandt number Pr=0.7. It has been found that these parameters affect considerably the considered flow characteristics. A comparison with earlier results for a Newtonian fluid (K=0) shows a good agreement.
19
Content available remote Thermophoresis free convection from a vertical cylinder embedded in a porous medium
Chamkha A. J., Jaradat M., Pop I.
International Journal of Applied Mechanics and Engineering
|
2004
|
Vol. 9, no 3
471-481
EN
This paper deals with the steady free convection over an isothermal vertical circular cylinder embedded in a fluid-saturated porous medium in the presence of the thermophoresis particle deposition effect. The governing partial differential equations are transformed into a set of non-similar equations, which are solved numerically using an implicit finite-difference method. Comparisons with the previously published work are performed and the results are found to be in excellent agreement. Many results are obtained and a representative set of these results is displayed graphically to illustrate the influence of the various physical parameters on the wall thermophoretic deposition velocity and concentration profiles.
20
Content available remote Hall effects on MHD plasma Couette flow in a rotating environment
Ghosh S. K., Pop I.
International Journal of Applied Mechanics and Engineering
|
2004
|
Vol. 9, no 2
293-305
EN
The Magnetohydrodynamic (MHD) plasma Couette flow in a rotating frame of reference subject to the Hall current is studied. This problem is confined to a startup process, which deals with an impulsive start of the moving plate as well as an accelerated start of the moving plate. The solution is obtained by employing the Laplace inversion method. An asymptotic behavior of the solution is analysed for small as well as large time T to gain the physical insight into the flow pattern. As a consequence of the physical situation of interest the fully ionized neutral plasma interacts with the frictional layer when it starts in motion. The dimensionless velocity profiles are depicted graphically and the shear stresses are presented in tables.
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