Chemical reaction and Soret effects on hydromagnetic micropolar fluid along a stretching sheet

AbstractFree convection effects of a micropolar fluid along a stretching sheet embedded in a porous medium in the presence of a volumetric non-uniform heat source is investigated in the present paper. Thermal diffusion and first order chemical reaction are also considered in the present study to govern the flow characteristic. The generalization of the earlier studies centers round: (i) The magnetohydrodynamic flow is made to pass through a porous medium characterized by a non-Darcian drag coefficient affecting the momentum equation. (ii) The energy equation is modified with the interplay of non-uniform heat source. (iii) Consideration of chemically reactive species characterized by first order chemical reaction and thermal diffusion i.e. Soret modifying the equation of species concentration. Similarity transformation technique is used to transform the governing nonlinear partial differential equations into ordinary differential equations. The numerical solutions are achieved showing the effects of pertinent parameters. For verification of the present findings the results of this study have been compared with the earlier works in particular cases

Palaeomagnetism and magnetostiatigraphy of Triassic strata in the Sangre de Cristo Mountains and Tucumcari Basin, New Mexico, USA

We report palaeomagnetic data and a composite magnetic polarity sequence for Middle and Upper Triassic rocks assigned to the Anton Chico Member of the Moenkopi Formation and Chinle Group, respectively, exposed along the eastern flank of the Sangre de Cristo Mountains and in the Tucumcari Basin of eastern and northeastern New Mexico. Thermal demagnetization isolates a well-defined, dual polarity, characteristic magnetization, carried in most cases by haematite and interpreted as an early acquired chemical remanent magnetization (CRM). Characteristic magnetizations from 74 palaeomagnetic sites (one site = one bed) are used to define a magnetic polarity sequence, which we correlate with previously published Triassic data obtained from both marine and non-marine rocks. Preliminary correlation suggests that the resolution of magnetostratigraphic data derived from continental strata is not necessarily of lesser quality than that from marine rocks. On the basis of the magnetostratigraphic data, a profound unconformity is believed to separate lower-middle Norian and upper Norian-Rhaetian strata of the Chinle Group. Palaeomagnetic poles derived from selected sites in steeply dipping (> 85°) strata for the Middle Triassic (Anisian, ∼240 Ma: 50°N 121°E; N = 8), late Carman-early Norian (∼225 Ma: 53°N 104°E; N = 16), and late Norian-Rhaetian (∼208 Ma: 59°N 77°E; N = 8) are in relatively good agreement with previously published data for the Moenkopi Formation and Chinle Group and related strata in southwest North America. None the less, comparison with palaeomagnetic poles obtained from gently dipping or flat-lying Triassic strata from this study (Anisian, 46°N 112°E; N = 13; late Carnian, 54°N 87°E; N =12) and previously published Triassic poles in southwest North America suggest that a modest ‘apparent rotation’ not greater than about 5° affects declinations from steeply dipping rocks. The distribution of palaeomagnetic poles indicates ∼25° (angular distance) of apparent polar wander between about 240 and 208 Ma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73972/1/j.1365-246X.1996.tb05646.x.pd

Study of heat and mass transfer on MHD Walters B′ nanofluid flow induced by a stretching porous surface

This communication deals with the role of heat and mass transfer in a Walters B′ (non-Newtonian) nanofluid fluid flow through a stretching vertical porous surface. The behavior of Brownian motion, chemical reaction, thermophoresis and heat generation/absorption are also taken into consideration. A suitable similarity transformation variable is utilized to model the equations of nanoparticle concentration, momentum, and thermal energy. These ordinary differential equations are solved analytically by means of perturbation technique and then solved numerically using fourth-fifth order Runge–Kutta method. The behavior of all the sundry parameters are discussed and demonstrated via graphs. Furthermore, Sherwood number, Nusselt number and skin friction coefficient are also displayed via graphs. A numerical comparison is also presented against skin friction coefficient, Nusselt number and Sherwood number with previously published data. Keywords: Non-Newtonian nanofluid, Vertical stretching surface, Heat source/sink, Chemical reaction, Magnetic fiel

Chemical reaction effect on MHD free convective surface over a moving vertical plate through porous medium

An attempt has been made to study the heat and mass transfer effect in a boundary layer flow of an electrically conducting viscous fluid subject to transverse magnetic field past over a moving vertical plate through porous medium in the presence of heat source and chemical reaction. The governing non-linear partial differential equations have been transformed into a two-point boundary value problem using similarity variables and then solved numerically by fourth order Runge–Kutta fourth order method with shooting technique. Graphical results are discussed for non-dimensional velocity, temperature and concentration profiles while numerical values of the skin friction, Nusselt number and Sherwood number are presented in tabular form for various values of parameters controlling the flow system

Entropy generation analysis for viscoelastic MHD flow over a stretching sheet embedded in a porous medium

In this paper it is intended to analyse entropy generation by applying second law of thermodynamics to magnetohydrodynamic flow, heat and mass transfer of an electrically conducting viscoelastic liquid (Walters B′) past on a stretching surface, taking into account the effects of Joule dissipation, viscous dissipation and Darcy dissipation, and internal heat generation. The boundary layer equations are solved analytically by using Kummer’s function. The entropy generation has been computed considering Darcy dissipation besides viscous and Joule dissipation. Results for some special cases of the present analysis are in good agreement with the existing literature. Increase in viscoelastic and magnetic parameter reduces the velocity. Increase in elastic parameter causes a greater retardation in the velocity. Presence of porous matrix enhances temperature whereas increase in Prandtl number decreases the temperature. One striking result of the present study is that Darcy dissipation favours higher level entropy generation in all the cases except the flow of liquid with low thermal diffusivity assuming the process to be irreversible

Numerical investigation on MHD micropolar fluid flow toward a stagnation point on a vertical surface with heat source and chemical reaction

In this paper, the steady magnetohydrodynamic (MHD) mixed convection stagnation point flow of an incompressible and electrically conducting micropolar fluid past a vertical flat plate is investigated. The effects of induced magnetic field, heat generation/absorption and chemical reaction have been taken into account during the present study. Numerical solutions are obtained by using the Runge–Kutta fourth order scheme with shooting technique. The skin friction and rate of heat and mass transfer at the bounding surface are also calculated. The generality of the present study is assured of by discussing the works of Ramachandran et al. (1988), Lok et al. (2005) and Ishak et al. (2008) as particular cases. It is interesting to note that the results of the previous authors are in good agreement with the results of the present study tabulated which is evident from the tabular values. Further, the novelty of the present analysis is to account for the effects of first order chemical reaction in a flow of reactive diffusing species in the presence of heat source/sink. The discussion of the present study takes care of both assisting and opposing flows. From the computational aspect, it is remarked that results of finite difference (Ishak et al. (2008)) and Runge–Kutta associated with shooting technique (present method) yield same numerical results with a certain degree of accuracy. It is important to note that the thermal buoyancy parameter in opposing flow acts as a controlling parameter to prevent back flow. Diffusion of lighter foreign species, suitable for initiating a destructive reaction, is a suggestive measure for reducing skin friction