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Some serious errors exist in the above paper. Many concentration profiles are truncated and wrong. The local similarity method used is not correct. The dimensionless Hartmann number is dimensional and wrong. [ABSTRACT FROM AUTHOR]

Some serious errors exist in the above paper. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

The flow past a sphere, rigidly held between two parallel plates (Couette flow), was studied in a non-Newtonian, power-law fluid, numerically. The three momentum equations have been solved under the following conditions: creeping flow with Re < 1; power-law index 0.2–1; distance of sphere center from the plates 1.15–10; sphere position between the plates 0.1–0.9. Diagrams have been produced for the direct calculation of the force acting on the sphere. The numerical forecast shows a significant disparity between Newtonian and non-Newtonian fluids. All in all, the wall effect in power law fluids is less extreme than in Newtonian fluids. Furthermore, in non-Newtonian fluids, the force changes linearly when the sphere approaches the upper plate. [ABSTRACT FROM AUTHOR]

The flow of a non-Newtonian, power-law fluid, directed normally to a rotating sphere is considered in the present paper. The problem is investigated by means of a three-dimensional numerical simulation with the SIMPLE algorithm. The investigation covers the power-law index from 0.2 up to 2, rotation rate from 0.1 up to 3 and Reynolds number from 0.1 up to 100. The following general rules are valid. The lift coefficient increases with increasing the rotation rate. At high Re numbers the drag coefficient increases with the power-law index. At high Re numbers the torque coefficient increases with the power-law index and with the rotation rate, whereas the torque coefficient reduces as the Reynolds number increases. In addition, there are some special cases which are analyzed in the text. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

In the above paper, there are some typographical errors and some serious errors. [ABSTRACT FROM AUTHOR]

The flow induced by a sphere rotating inside a non-Newtonian, Bingham fluid has been investigated numerically. The rotating sphere is enclosed in a concentric cubic box with solid boundaries. The Bingham number varied between 0.01 and 100,000 and the Reynolds number varied between 0.01 and 10,000. The torque increases with the Bingham number and reaches an asymptotic state at large Bn. The torque is independent of the Reynolds number at high Bn. The yielded region around the sphere has been determined and an empirical equation is found for its extent. [ABSTRACT FROM AUTHOR]

A serious error exists in the above paper. [ABSTRACT FROM AUTHOR]

The correct form is 5 HT ht Graph Fourth error (serious) The equation (21) in [[1]] is as follows 6 HT ht Graph Equation (6) is a dimensionless equation presented in [[1]] after the non-dimensionalization in equation (17) in [[1]]. [Extracted from the article]

The flow around a horizontal square cylinder with uniform suction or injection at the front and rear sides is considered in the present paper. The problem is investigated numerically with a finite volume method using the SIMPLE algorithm. This flow has been investigated in the past for Reynolds numbers greater than 70. In the present work, the investigation is extended to very low Reynolds numbers (up to 0.001, Stokes flow) including eight different cases concerning suction-injection at the two sides. It is found that the drag coefficient takes negative and zero values in many cases and varies linearly at low Re numbers. In all eight cases, the vortices around the cylinder have been calculated. It is found that at low Re numbers, some vortices are symmetrical both about the horizontal and vertical cylinder axes. [ABSTRACT FROM AUTHOR]

The present comment concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]

All velocity profiles in the above paper appear to be questionable and thus may include serious numerical deviations with respect to the correct solutions. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

The flow of a non-Newtonian, Carreau fluid, directed normally to a horizontal, stationary, circular cylinder is considered in the present paper. The problem is investigated numerically using the commercial code ANSYS FLUENT with a very large calculation domain in order that the flow could be considered unbounded. The investigation covers the power-law index from 0.2 up to 2, the Reynolds number range from 0.1 up to 40 and the Carreau number from 0.1 up to 20. Wake lengths and drag coefficients have been calculated for many combinations of the above three parameters. At low power-law index the wake length changes non-linearly with increasing Reynolds number and as the power-law index rises the variation becomes linear. The drag coefficient reduces in shear-thinning fluids and grows in shear-thickening fluids with increasing Carreau number. At the same Carreau number the drag coefficient is higher is shear-thickening fluids compared to that of shear-thinning fluids. [ABSTRACT FROM AUTHOR]

Some suspicious equations and scientific inaccuracies of the aforementioned paper are concerned in this comment. [ABSTRACT FROM AUTHOR]

In a recent paper by Makinde and Olanrewaju (J Fluids Eng 132:044502, ) the effect of thermal buoyancy along a stationary vertical plate with a uniform free stream flow was considered. The plate's wall thermal boundary condition and the fluid thermal expansion coefficient were variable along the plate in order that the problem accepts a similarity solution. In the present work, the problem has been changed to have a constant heat transfer coefficient and a constant thermal expansion coefficient which is considered to be more realistic and has much more practical applications. The present problem is non-similar and results are obtained by numerical solution of the governing equations. The problem is governed by the Prandtl number, the non-dimensional distance along the plate and the convective Grashof number. It is found that the wall shear stress, the wall heat transfer and the wall temperature all increases with increasing distance and the wall temperature tends to 1. The influence of the convective Grashof number is to increase the wall shear stress and the wall heat transfer and to reduce the wall temperature. [ABSTRACT FROM AUTHOR]

The present note treats a special case of a previous work published in Acta Mechanica (Kumari and Nath in Acta Mech 146:139-150, 2001). Analytical and asymptotic solutions are presented not found in the previous paper. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

In the above paper a theoretical investigation of MHD convective flow and heat transfer of an incompressible viscous nanofluid past a porous vertical stretching sheet in the presence of variable stream condition is presented. The governing boundary layer equations are transformed by a Lie symmetry group transformation and the ordinary differential equations are solved numerically using Runge-Kutta Gill method. [ABSTRACT FROM AUTHOR]

The characteristics of the boundary layer flow past a plane surface adjacent to a saturated Darcy-Brinkman porous medium are investigated in this paper. The flow is driven by an external free stream moving with constant velocity. The surface is heated with a convective boundary condition with constant heat transfer coefficient. The problem is non-similar and is investigated numerically by a finite difference method. The problem is governed by four non-dimensional parameters, that is, the convective Darcy number, the convective Grashof number, the Prandtl number, and the axial distance along the plate. The influence of these parameters on the results is investigated, and the results are presented in tables and figures. The Darcy term and the Grashof term in the momentum equation contradict each other and this contradiction makes the problem complicated. However, the wall shear stress and the wall temperature increase continuously along the plate and the wall temperature always tends to 1. [ABSTRACT FROM AUTHOR]

In a recent paper by Bataller (Appl Math Comput 198 333-338, ) the effect of radiation on the classical Blasius flow along a stationary plate in a horizontal free stream was considered. The results in that paper have been produced using a linearized Rosseland approximation, which is valid only for small temperature differences between the plate and the ambient fluid. In the present work, we extend the above work to non-linear Rosseland approximation which is valid for both small and large temperature differences. [ABSTRACT FROM AUTHOR]

The flow of a fluid past a flat plate of finite length and infinite width (two-dimensional flow) is considered. The plate is heated by convection from a fluid with constant temperature T with a constant heat transfer coefficient h. In all previous works, the problem was considered using boundary layer theory whereas, in the present work, the solution is based on the full Navier-Stokes equations. The problem is investigated numerically with a finite volume method using the commercial code ANSYS FLUENT. The governing parameters are the Reynolds number, the new heat transfer parameter, and the Prandtl number. In addition, the influence of these three parameters on the temperature field is investigated. It is found that high Reynolds and high Prandtl numbers the wall temperature increases along the plate. They reach a maximum near the trailing edge then decrease. The same occurs as the heat transfer parameter increases. When the Reynolds and Prandtl numbers are low, the plate temperature tends to become symmetric, with a maximum at the middle of the plate. The temperature profiles become thicker as the Reynolds number and the Prandtl number is reduced while the temperature profiles become thicker as the heat transfer parameter increases. [ABSTRACT FROM AUTHOR]

Some serious errors exist in the above paper. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

The flow of a non-Newtonian, power-law fluid directed either tangentially or normally to a flat plate of finite length and infinite width (two-dimensional flow) is considered. The problem is investigated numerically using the code ANSYS FLUENT. This problem has been investigated in the past but only for shear-thinning fluids ( n < 1). We extend the investigation for the case of shear-thinning, Newtonian and shear-thickening fluids, covering a wide range of Reynolds numbers (from very low to very high). For low Reynolds numbers and low power-law index ( n < 0.6) the drag coefficient obeys the relationship c = A/Re, both for tangential and normal flow. Equations for the quantity A have been derived as functions of the power-law index. For normal flow, the drag coefficient tends to become independent of the power-law index, both for shear-thinning and shear-thickening fluids at high Reynolds numbers. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of variable fluid properties (density, viscosity, thermal conductivity and specific heat) on the convection in the classical Rayleigh-Bénard problem is investigated. The investigation concerns water, air, and engine oil by taking into account the variation of fluid properties with temperature. The results are obtained by numerically solving the governing equations, using the SIMPLE algorithm and covering large temperature differences. It is found that the critical Rayleigh number increases as the temperature difference increases considering all fluid properties variable. However, when the fluid properties are kept constant, calculated at the mean temperature, and only density is considered variable, the critical Rayleigh number either decreases or remains constant. [ABSTRACT FROM AUTHOR]

The Blasius and Sakiadis flows of a non-Newtonian power-law conducting fluid under the effect of a constant transverse magnetic field is considered. The boundary layer equations are transformed into a non-dimensional form and a new dimensionless magnetic parameter is introduced. The transformed boundary layer equations are solved with a finite difference method. Both Blasius and Sakiadis flows reach an asymptotic state and become one-dimensional with the increase of the coordinate in the streamwise direction. The flow behavior in the intermediate region is studied and exact analytical solutions have been found for the asymptotic state. The characteristics of physical and engineering interest are discussed in the paper in detail. [ABSTRACT FROM AUTHOR]

The steady forced convection flow of a power-law fluid over a horizontal plate embedded in a saturated Darcy-Brinkman porous medium is considered. The flow is driven by a constant pressure gradient. In addition to the convective inertia, also the “porous Forchheimer inertia” effects are taken into account. The pertinent boundary value problem is investigated analytically, as well as numerically by a finite difference method. It is found that far away from the leading edge, the velocity boundary layer always approaches an asymptotic state with identically vanishing transverse component. This holds for pseudoplastic (0 < n < 1), Newtonian ( n = 1), and dilatant ( n > 1) fluids as well. The asymptotic solution is given for several particular values of the power-law index n in an exact analytical form. The main flow characteristics of physical and engineering interest are discussed in the paper in some detail. [ABSTRACT FROM AUTHOR]

We investigate the fully developed flow in a fluid-saturated porous medium channel with an electrically conducting fluid under the action of a parallel Lorentz force. The Lorentz force varies exponentially in the vertical direction due to low fluid electrical conductivity and the special arrangement of the magnetic and electric fields at the lower plate. Exact analytical solutions are derived for fluid velocity and the results are presented in figures. All these flows are new and are presented for the first time in the literature. [ABSTRACT FROM AUTHOR]

The work of Mahmood and Merkin (ZAMP 39:186–203, 1988) concerns the mixed convection flow along a stationary cylinder in a constant free stream. In the present note, we extend the above work to general situations involving a moving cylinder. [ABSTRACT FROM AUTHOR]

Some errors exist in the above paper. [ABSTRACT FROM AUTHOR]

In the above paper a dimensionless parameter is wrong and many profiles are truncated and wrong. [ABSTRACT FROM AUTHOR]

A serious error exists in the above paper. [ABSTRACT FROM AUTHOR]

The dimensional horizontal momentum equation in Hussain et al. ([1]) is 1 HT ht Graph where I i SB I e i sb is the electric charge density and I E i SB I z i sb ( I i SP 1/2 sp I kg i SP 1/2 sp sec SP -3/2 sp ) is the electric field along the I z i axis. [Extracted from the article]

The present discussion concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]

Some errors have been found in the above paper. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Similarity Analysis in Magnetohydrodynamics: Hall Effects on Forced Convective Heat and Mass Transfer of Non-Newtonian Power Law Fluids Past a Semi-Infinite Vertical Flat Plate," by A.A. Afify, E.M. Aboeldahab and E.S. Mohamed.

In Physics it is not allowed to add quantities with different units and for that reason the term HT ht is wrong. [Extracted from the article]

The present comment concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]

The present comment concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]

The present comment concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]

A numerical investigation of transient magnetohydrodynamic free convection flow past an infinite vertical plate embedded in a porous medium with viscous dissipation is presented in the above paper. The governing differential equations are transformed into a set of non-linear coupled partial differential equations and are solved numerically using the finite element method. Numerical results for the velocity, temperature and concentration profiles within the boundary layer are presented and discussed. [ABSTRACT FROM AUTHOR]

The present comment concerns some doubtful results included in the above paper. [ABSTRACT FROM AUTHOR]