Radiation and magnetic field effects on the unsteady mixed convection flow of a second grade fluid over a vertical stretching sheet

This present analysis discusses the mixed convection boundary layer flow of a magnetohydrodynamic second grade fluid over an unsteady permeable stretching sheet. The time‐dependent stretching velocity and the surface temperature are chosen. Series solutions of the governing boundary value problems are obtained by employing homotopy analysis method. Convergence of the obtained solution is explicitly discussed. The dependence of velocity and temperature profiles on the various quantities is shown and discussed by plotting graphs. Skin friction coefficient and the local Nusselt number tabulated and analyzed. Copyright © 2010 John Wiley & Sons, Ltd.     

MHD peristaltic flow of a third order fluid in an asymmetric channel

This study is concerned with peristaltic flow of a magnetohydrodynamic (MHD) fluid in an asymmetric channel. Asymmetry in the flow is induced by waves on the channel walls having different amplitudes and phase. A systematic approach based on an expansion of Deborah number is used for the solution series. Analytic expressions have been developed for the stream function, axial velocity and axial pressure gradient. The pressure rise over a wavelength has been addressed through numerical integration. Particular attention has been given to the effects of Hartman number and Deborah number on the pressure rise over a wavelength and the trapping phenomenon. Several limiting solutions of interest are obtained as the special cases of the presented analysis by taking the appropriate parameter(s) to be zero. Copyright © 2009 John Wiley & Sons, Ltd.     

Boundary layer flow of a Jeffrey fluid with convective boundary conditions

The boundary layer stretched flow of a Jeffrey fluid subject to the convective boundary conditions was investigated. The governing dimensionless problems were computed by using the homotopy analysis approach. Convergence of the derived solutions was checked and the influence of embedded parameters was analyzed by plotting graphs. It was noticed that the velocity increases with an increase in the Deborah number. Furthermore, it was found that the temperature is also an increasing function of the Biot number. We further found that for fixed values of other parameters, the local Nusselt number increases by increasing the suction parameter and Deborah number. Numerical values of the skin friction coefficient and local Nusselt numbers were computed and examined. Copyright © 2011 John Wiley & Sons, Ltd.     

Similar solutions of stretching flow with mass transfer

This study describes the influence of mass transfer on the steady two‐dimensional magnetohydrodynamic boundary layer flow of a Jeffery fluid bounded by a stretching sheet. A uniform magnetic field in the presence of chemical reaction is applied. The arising nonlinear partial differential equations are reduced to nonlinear ordinary differential equations by similarity variables. Similar solutions of velocity and concentration fields are derived by a homotopy analysis method. The values of surface mass transfer and gradient of mass transfer are also tabulated. Copyright © 2009 John Wiley & Sons, Ltd.     

Biomimetic processes. IV. Carbocationic polymerization of isoprene initiated by dimethyl allyl alcohol

In this article, we investigate a new bio‐inspired synthetic route towards NR homologs based on the carbocationic polymerization of isoprene initiated by dimethyl allyl alcohol (DMAOH)/TiCl₄ or BF₃.Et₂O as the catalytic system. This study is the continuation of our studies related to the proof of principle that NR biosynthesis is based on a carbocationic mechanism. It is shown that using the biomimetic strategy of initiation by allylic carbocations, polyisoprene carrying a dimethyl allyl head group is produced almost exclusively via 1,4 addition, yielding repeating units with cis and trans configurations. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2181–2189, 2009     

Analytical solution for the steady flow of the third grade fluid in a porous half space

In this study, we model the flow of a third grade fluid in a porous half space. Based on modified Darcy’s law, the flow over a suddenly moved flat plate is discussed analytically by using homotopy analysis method (HAM). The influence of various parameters of interest on the velocity profile is seen.     

Couette flow of a third grade fluid with rotating frame and slip condition

An incompressible third grade fluid occupies the porous space between two rigid infinite plates. The steady rotating flow of this fluid due to a suddenly moved lower plate with partial slip of the fluid on the plate is analysed. The fluid filling the porous space between the two plates is electrically conducting. The flow modeling is developed by employing a modified Darcy’s law. A numerical solution of the governing problem consisting of a non-linear ordinary differential equation and non-linear boundary conditions is obtained and discussed. Several limiting cases of the arising problem can be obtained by choosing suitable parameters.     

Exact solutions of second grade aligned MHD fluid with prescribed vorticity

We present here the exact solutions for the equations of magnetohydrodynamic (MHD) aligned flow of a second grade fluid. The exact solutions are constructed for steady and unsteady equations by employing inverse method.     

Heat transfer in unsteady axisymmetric second grade fluid

This work looks at the heat transfer effects on the flow of a second grade fluid over a radially stretching sheet. The axisymmetric flow of a second grade fluid is induced due to linear stretching of a sheet. Mathematical analysis has been carried out for two heating processes, namely (i) with prescribed surface temperature (PST case) and (ii) prescribed surface heat flux (PHF case). The modelled non-linear partial differential equations in two dependent variables are reduced into a partial differential equation with one dependent variable. The resulting non-linear partial differential equations are solved analytically using homotopy analysis method (HAM). The series solutions are developed and the convergence is properly discussed. The series solutions and graphs of velocity and temperature are constructed. Particular attention is given to the variations of emerging parameters such as second grade parameter, Prandtl and Eckert numbers.     

Interaction of point defects with twin boundaries in Au： A molecular dynamics study

The molecular dynamics simulation technique with many-body and semi-empirical potentials （based on the embedded atom method potentials） has been used to calculate the interactions of point defects with （1 1 1）, （1 1 3）, and （1 2 0） twin boundaries in Au at different temperatures. The interactions of single-, di-, and tri-vacancies （at on- and off-mirror sites） with the twin interfaces at 300 K are calculated. All vacancy clusters are favorable at the on-mirror arrangement near the （1 1 3） twin boundary. Single- and di-vacancies are more favorable at the on-mirror sites near the （1 1 l） twin boundary, while they are favorable at the oft-mirror sites near the （1 2 0） twin boundary. Almost all vacancy clusters energetically prefer to lie in planes closest to the interface rather than away from it, except for tri-vacancies near the （1 2 0） interface at the off-mirror site and for 3.3 and 3.4 vacancy clusters at both sites near the （1 1 1） interface, which are favorable away from the interface. The interaction energy is high at high temperatures.