Showing papers in "International Journal of Fluid Mechanics Research in 2005"
23 citations
TL;DR: In this article, the flow characteristics over a NACA 4415 airfoil are studied experimentally at a Reynolds number of 2.4 • 105 by varying the angle of attack from 0 to 10° and ground clearance of the trailing edge from five percent of chord to eighty percent.
Abstract: The flow characteristics over a NACA 4415 airfoil are studied experimentally at a Reynolds number of 2.4 • 105 by varying the angle of attack from 0 to 10° and ground clearance of the trailing edge from five percent of chord to eighty percent. The pressure distribution on the airfoil surface was obtained, velocity survey over the surface was performed, wake region was explored and lift and drag forces were measured. A strong suction effect was observed on the lower surface for angles of attack of 0 and 2.5° at small ground clearances. For the angle of attack of 0°, a separation bubble formed on the lower surface for the smallest ground clearance while for 2.5°, laminar separation occurred from the lower surface well ahead of the trailing edge. Increased suction was observed on the upper surface for small ground clearances. For the angle of attack of 10°, the flow on the upper surface could not withstand the adverse pressure gradient at small ground clearances and separated from the surface resulting in a loss of lift and an increase in drag.
22 citations
18 citations
TL;DR: In this paper, the effects of all parameters on velocity, temperature, skin friction, and heat transfer rate (Nusselt number) are graphically presented and tabulated, and discussed in detail.
Abstract: Unsteady natural convection flow of a viscous, incompressible, electrically conducting fluid past an infinite vertical porous plate embedded within a saturated, highly porous medium under the influence of a uniform magnetic field, Eckert heating, and a heat-absorbing sink is studied. It is assumed that the suction velocity is subjected to small-amplitude oscillations in time about the steady nonzero mean suction velocity. Approximate solutions for the velocity and temperature field are obtained using the multiparameter perturbation technique. Expressions for skin friction and rate of heat transfer are also derived. Mean temperatures are boosted by both magnetic field and heat-source parameter, but are lowered by a rise in the Prandtl number, Grashof number, and permeability parameter (k). The effects of all parameters on velocity, temperature, skin friction, and heat transfer rate (Nusselt number) are graphically presented and tabulated, and are discussed in detail. The model finds applications in nuclear heat transfer processes, metallurgy, aerospace/aval propulsion, and energy systems.
15 citations
TL;DR: In this paper, convective heat transfer flow in a rotating fluid over a vertical plate in a non-Darcian thermally-stratified high-porosity medium is studied.
Abstract: The convective heat transfer flow in a rotating fluid over a vertical plate in a non-Darcian thermally-stratified high-porosity medium is studied. The governing partial differential equations for momentum and energy are solved numerically using Blottner's finite-difference method. The effects of Rossby number and various thermal parameters on velocities, temperature, skin friction and Nusselt number are presented graphically and discussed at length. The flow and temperature fields are strongly influenced by the thermal stratification, porosity, inertia and Rossby number, whereas they demonstrate a weak dependence on the permeability parameter. Beyond a critical value of the Rossby number (Ro ≥ 0.5) flow reversal occurs in the X-component of the velocity. Other flow phenomena including primary and secondary flows are discussed. The problem finds applications in rotating industrial and geophysical systems.
14 citations
TL;DR: In this article, an analysis of convection-radiation interaction heat transfer in boundary-layer flows over a semi-infinite flat plate with temperature dependent effective viscosity embedded in a fluid-saturated porous medium in the presence of a magnetic field was presented.
Abstract: An analysis is presented for the convection-radiation interaction heat transfer in boundary-layer flows over a semi-infinite flat plate with temperature dependent effective viscosity embedded in a fluid-saturated porous medium in the presence of a magnetic field. The conservation equations that govern the problem were reduced to a dimensionless form. The system was solved numerically by the Keller-box method. Asymptotic solutions for small and large values of the distance from the leading edge of the plate are presented. The influence of the various parameters entering into the problem on the velocity and heat transfer is studied.
11 citations
9 citations
TL;DR: In this article, the authors investigated the effect of viscous dissipation on natural convection from a vertical plate placed in a thermally stratified environment and integrated the reduced equations by employing the implicit finite difference scheme of Keller box method.
Abstract: In the present study we investigate the effect of viscous dissipation on natural convection from a vertical plate placed in a thermally stratified environment. The reduced equations are integrated by employing the implicit finite difference scheme of Keller box method and obtained the effect of heat due to viscous dissipation on the local skin friction and local Nusselt number at various stratification levels, for fluids having Prandtl numbers of 10, 50, and 100. Solutions are also obtained using the perturbation technique for small values of viscous dissipation parameters $\xi$ and compared to the finite difference solutions for 0 · $\xi$ · 1. Effect of viscous dissipation and temperature stratification are also shown on the velocity and temperature distributions in the boundary layer region.
9 citations
TL;DR: In this paper, a mathematical model of the geophysical vortex flow using an order-of-magnitude analysis based on a laminar, steady axisymmetric vortex motion in a cylindrical frame of reference is developed.
Abstract: A mathematical model is developed of the geophysical vortex flow using an order-of-magnitude analysis based on a laminar, steady axisymmetric vortex motion in a cylindrical frame of reference. A similarity method is adopted. The classical solution of Long (J. Fluid. Mech., 11, p. 611, 1961; Rossby number > 1) is reexamined. It is shown that true similarity solutions for the intermediate case of the Rossby number ∼ 1 do not exist, since this implies the physically impossible vortex flow wherein the fluxes of radial momentum and angular momentum are simultaneously zero. Numerical solutions are presented for our model using a shooting method with graphs depicting the variation of pressure and also axial, azimuthal, and radial velocities with non-dimensional radius parameter. The results are discussed with applications to tornado swirl and compared to the earlier studies by Long and Herbert.
9 citations
TL;DR: In this paper, an analytical study of free convection in fully developed laminar, free-convection flow of two viscous, immiscible, incompressible liquids bounded above and blow by two parallel naturally permeable beds of high porosity and finite thickness is presented.
Abstract: The present paper deals with an analytical study of free convection in fully developed laminar, free convection flow of two viscous, immiscible, incompressible liquids bounded above and blow by two parallel naturally permeable beds of high porosity and finite thickness. The momentum transfer in the free flow region is governed by Navier-Stokes equations and the flow in the porous medium is governed by Brinkman equation. The flow domain is divided into four regions and exact solutions of the momentum and energy equations are obtained for each region under appropriate matching and boundary conditions. The effects of various parameters on the velocity and temperature fields are discussed with the help of graphs while the effects on skin-friction and heat transfer are discussed with the help of tables.
8 citations
TL;DR: In this paper, a numerical study for transient natural convection heat transfer of a micropolar boundary layer flow near a vertical isothermal surface is presented, where the governing equations are formulated and solved numerically using the MackCormak's technique.
Abstract: In recent years, the dynamics of micropolar fluids, originated from the theory of Eringen, has been a popular area of research. As the fluids consist of randomly oriented molecules, and as each volume element of the fluid has translational as well as rotational motions, the analysis of physical problems in these fluids has revealed several interesting phenomena, which are not found in Newtonian fluids. The present study presents a numerical study for transient natural convection heat transfer of a micropolar boundary layer flow near a vertical isothermal surface. The governing equations are formulated and solved numerically using the MackCormak’s technique. A comparison with previously published results on special cases of the problem shows excellent agreement. Representative results for the velocity, micro-rotation and temperature profiles are shown graphically for different values of material parameters. In general, it is found that the temperature increases inside the boundary layer for the micropolar flows as compared to the Newtonian flows.
TL;DR: In this article, the thermal instability of electrically conducting incompressible micropolar fluid heated from below in the presence of uniform magnetic field under the action of rotation in porous and non-porous medium is investigated.
Abstract: In this paper, the thermal instability of electrically conducting incompressible micropolar fluid heated from below in the presence of uniform magnetic field under the action of rotation in porous and non-porous medium is investigated. Frequency equations are derived and Rayleigh number is determined. It is found that in both porous and non-porous medium, the variation of Rayleigh number with wavenumber is decreasing. However, the Rayleigh number is found to increase with increase of rotation parameter. This shows that the rotation has stabilizing effect in both cases. The results of some earlier workers have been reduced from the present formulation.
TL;DR: In this paper, a one-dimensional four-species sequential reactive contaminant transport model with spatially-dependent dispersion coefficient and transport velocity is considered and the general governing equations are non-dimensionalized and solved numerically by an efficient implicit iterative tri-diagonal finite-difference method.
Abstract: A one-dimensional four-species sequential reactive contaminant transport model with spatially-dependent dispersion coefficient and transport velocity is considered. The sequential reactions which take place are assumed to be nonlinear and of arbitrary order. Two types of variations of the dispersion coefficient with the downstream distance are considered. The first type assumes that the dispersivity increases as a power function with distance while the other assumes an exponentially-increasing function. The transport velocity is also assumed to follow a general power-law function with the space coordinate. The general governing equations are non-dimensionalized and solved numerically by an efficient implicit iterative tri-diagonal finite-difference method. Comparisons with previously published analytical solutions for special cases of the problem are performed and found to be in excellent agreement. A parametric study of all physical parameters is conducted and the results are presented graphically to illustrate interesting features of the solutions. It is found that the chemical reaction order, the scale-dependent dispersion coefficient and the non-uniform transport velocity have significant effects on the multi-species concentration profiles. * * * Nomenclature
TL;DR: A numerical solution of the effect of small but fluctuating gravitational field, characteristic of g-jitter, on the free convection boundary layer flow near a three-dimensional stagnation point of attachment resulting from a step change in its surface temperature and immersed in a micropolar fluid is presented in this article.
Abstract: A numerical solution of the effect of small but fluctuating gravitational field, characteristic of g-jitter, on the free convection boundary layer flow near a three-dimensional stagnation point of attachment resulting from a step change in its surface temperature and immersed in a micropolar fluid is presented in this paper. The case when the spin gradient on the wall is zero (strong concentration of the microelements) is considered. The transformed non-similar boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method to investigate the effects of variations in the forcing amplitude parameter, , forcing frequency parameter, , curvature ratio parameter, c, and micropolar parameter, K, on the skin friction and on the rate of heat transfer. The results are given for a value of the Prandtl number Pr 0.72. It has been found that these parameters affect considerably the considered flow and heat transfer characteristics. The comparison with earlier results for a Newtonian fluid (K 0) is shown to be very good.
TL;DR: In this article, the complex flow past a delta winglet-pair placed in a rectangular channel is studied numerically using the Large eddy Simulation (LES) approach, which is based on Marker and Cell algorithm with third order upwind scheme for the convective term.
Abstract: In the present investigation the complex flow past a delta winglet-pair placed in a rectangular channel is studied numerically using the Large eddy Simulation (LES) approach. The Reynolds number based on the channel height and inlet velocity is 10000. A grid of 165 × 45 × 95 is used. The code is based on Marker and Cell algorithm with third order upwind scheme for the convective term. The computed results are compared with experimental data at Reynolds number of 134000. The Reynolds number in computation is lower due to limitation of computing resources but the computations are able to capture the essential features and show qualitative agreement with experimental data. Computation show that the longitudinal velocities generated by the winglet-pair disrupt the growth of boundary layer and would serve ultimately to bring about enhancement of heat transfer between fluid and neighboring surface. Many features of flow, which are difficult to measure experimentally, can be obtained from the LES study.
TL;DR: In this article, an analysis of the natural convection flow in a rotating fluid over a vertical plate embedded in a thermally stratified high-porosity medium has been carried out.
Abstract: An analysis has been carried out to study the natural convection flow in a rotating fluid over a vertical plate embedded in a thermally stratified high-porosity medium. The nonlinear coupled parabolic partial differential equations have been solved numerically by using an implicit finite-difference scheme. The flow and temperature fields are strongly influenced by the thermal stratification, porosity, inertia, Rossby number, and Prandtl number, whereas they are weakly dependent on the permeability parameter.
TL;DR: In this paper, the problem of buoyancy-induced flow over a horizontal or a vertical flat plate embedded in a fluid-saturated non-Darcy porous medium is studied.
Abstract: In this article, the problem of buoyancy-induced flow over a horizontal or a vertical flat plate embedded in a fluid-saturated non-Darcy porous medium is studied. Forchheimer extension is considered in the flow equations. Similarity solutions for the transformed governing equations are obtained, with a prescribed variable surface temperature or variable surface heat flux, for each position of the plate. Values of the slip velocity, Nusselt number for variable surface temperature as well as excess surface temperature for variable surface heat flux, and the total heat transfer as well as the momentum flux, which are plotted in figures, have been presented for different values of the given parameters for the two cases of horizontal and vertical plates.