Finite element analysis of rotating oscillatory magneto-convective radiative micropolar thermo-solutal flow

Micropolar fluids provide an alternative mechanism for simulating micro-scale and molecular fluid mechanics which require less computational effort. In the present paper, a numerical analysis is conducted for the primary and secondary flow characterizing dissipative micropolar convective heat and mass transfer from a rotating vertical plate with oscillatory plate velocity, adjacent to a permeable medium. Owing to high temperature, thermal radiation effects are also studied. The micropolar fluid is also chemically-reacting, both thermal and species (concentration) buoyancy effects and heat source/sink are included. The entire system rotates with uniform angular velocity about an axis normal to the plate. Rosseland’s diffusion approximation is used to describe the radiative heat flux in the energy equation. The partial differential equations governing the flow problem are rendered dimensionless with appropriate transformation variables. A Galerkin finite element method is employed to solve the emerging multi-physical components of fluid dynamics problem are examined for a variety of parameters including rotation parameter, radiation-conduction parameter, micropolar coupling parameter, Eckert number (dissipation), reaction parameter, magnetic body force parameter and Schmidt number. A comparison with previously published article is made to check the validity and accuracy of the present finite element solutions under some limiting case and excellent agreement is attained. The current simulations may be applicable to various chemical engineering systems, oscillating rheometry, and rotating MHD energy generator near-wall flows

Mo (VI)/ZrO2 coated on honeycomb monolith as solid acid green catalyst for the acetylation of substituted alcohols and amines under solvent free conditions

553-561Honeycomb (HC) monolith coated with solid acids such as Mo (VI)/ZrO2 (MZ) with different Mo loadings (2, 6 and 10%) have been prepared by wet impregnation method and characterized by NH3 –TPD, BET surface area, PXRD, ICP-OES, SEM, TEM and EDAX techniques. These catalysts have been used as for the synthesis of O and N-acetylation reactions by the condensation of various alcohols with acetic anhydride under solvent free conditions in shorter times (20 min) at moderate temperature (70°C). Especially, 6% Mo (VI)/ZrO2 catalysts are found to be highly acidic and also resulted in high yields of O and N acetylated products up to ~99%. This methodology offers several advantages such as excellent yields, easy procedure, mild and environmentally benign conditions. MZ catalysts are found to be economical, efficient and highly active, recyclable and reusable up to 6 reaction cycles without much loss of their activity

Rotating unsteady multi-physico-chemical magneto-micropolar transport in porous media : Galerkin finite element study

In this paper, a mathematical model is developed for magnetohydrodynamic (MHD), incompressible, dissipative and chemically reacting micropolar fluid flow, heat and mass transfer through a porous medium from a vertical plate with Hall current, Soret and Dufour effects. The entire system rotates with uniform angular velocity about an axis normal to the plate. Rosseland’s diffusion approximation is used to describe the radiative heat flux in the energy equation. The governing partial differential equations for momentum, heat, angular momentum and species conservation are transformed into dimensionless form under the assumption of low Reynolds number with appropriate dimensionless quantities. The emerging boundary value problem is then solved numerically with a Galerkin finite element method employing the weighted residual approach. The evolution of translational velocity, micro-rotation (angular velocity), temperature and concentration are studied in detail. The influence of many multi-physical parameters in these variables is illustrated graphically. Finally, the friction factor, surface heat transfer and mass transfer rate dependency on the emerging thermo-physical parameters are also tabulated. The finite element code is benchmarked with the results reported in the literature to check the validity and accuracy under some limiting cases and an excellent agreement with published solutions is achieved. The study is relevant to rotating MHD energy generators utilizing non-Newtonian working fluids and also magnetic rheo-dynamic materials processing systems

A refined shear deformation theory for bending analysis of isotropic and orthotropic plates under various loading conditions

In this paper, a refined trigonometric shear deformation theory is applied for the bending analysis of isotropic and orthotropic plates under the various loading conditions. The two unknown variables are involved in the present theory. The present theory satisfies the shear stress free condition at top and bottom surface of the plates without using shear correction factors. The governing equations and boundary conditions are obtained by using the principle of virtual work. A closed form solution is obtained using Navier Solution Scheme. A simply supported isotropic and orthotropic plate subjected to sinusoidally distributed, uniformly distributed and linearly varying loads are considered for the detailed numerical study. The results obtained using present theory are compared with previously published results.

Numerical simulation of time-dependent non-Newtonian nano-pharmacodynamic transport phenomena in a tapered overlapping stenosed artery

Nanofluids are becoming increasingly popular in novel hematological treatments and also advanced nanoscale biomedical devices. Motivated by recent developments in this area, a theoretical and numerical study is described for unsteady pulsatile flow, heat and mass transport through a tapered stenosed artery in the presence of nanoparticles. An appropriate geometric expression is employed to simulate the overlapping stenosed arterial segment. The Sisko non-Newtonian model is employed for hemodynamic rheology. Buongiorno’s formulation is employed to model nanoscale effects. The two-dimensional non-linear, coupled equations are simplified for the case of mild stenosis. An explicit forward time central space (FTCS) finite difference scheme is employed to obtain a numerical solution of these equations. Validation of the computations is achieved with another numerical method, namely the variational finite element method (FEM). The effects of various emerging rheological, nanoscale and thermofluid parameters on flow and heat/mass characteristics of blood are shown via several plots and discussed in detail. The circulating regions inside the flow field are also investigated through instantaneous patterns of streamlines. The work is relevant to nanopharmacological transport phenomena, a new and exciting area of modern medical fluid dynamics which integrates coupled diffusion, viscous flow and nanoscale drug delivery mechanisms

Numerical study of self-similar natural convection mass transfer from a rotating cone in anisotropic porous media with Stefan blowing and Navier slip

A mathematical model is presented for laminar, steady natural convection mass transfer in boundary layer flow from a rotating porous vertical cone in anisotropic high permeability porous media. The transformed boundary value problem is solved subject to prescribed surface and free stream boundary conditions with a MAPLE 17 shooting method. Validation with a Chebyshev spectral collocation method is included. The influence of tangential Darcy number, swirl Darcy number, Schmidt number, rotational parameter, momentum (velocity slip), mass slip and wall mass flux (transpiration) on the velocity and concentration distributions is evaluated in detail. The computations show that tangential and swirl velocities are enhanced generally with increasing permeability functions (i.e. Darcy parameters). Increasing spin velocity of the cone accelerates the tangential flow whereas it retards the swirl flow. An elevation in wall suction depresses both tangential and swirl flow. However, increasing injection generates acceleration in the tangential and swirl flow. With greater momentum (hydrodynamic) slip, both tangential and swirl flows are accelerated. Concentration values and Sherwood number function values are also enhanced with momentum slip, although this is only achieved for the case of wall injection. A substantial suppression in tangential velocity is induced with higher mass (solutal) slip effect for any value of injection parameter. Concentration is also depressed at the wall (cone surface) with an increase in mass slip parameter, irrespective of whether injection or suction is present. The model is relevant to spin coating operations in filtration media (in which swirling boundary layers can be controlled with porous media to deposit thin films on industrial components), flow control of mixing devices in distillation processes and also chromatographical analysis systems

Experimental study of improved rheology and lubricity of drilling fluids enhanced with nano-particles

An experimental study of the rheology and lubricity properties of a drilling fluid is reported, motivated by applications in highly deviated and extended reach wells. Recent developments in nanofluids have identified that the judicious injection of nano-particles into working drilling fluids may resolve a number of issues including borehole instability, lost circulation, torque and drag, pipe sticking problems, bit balling and reduction in drilling speed. The aim of this article is therefore to evaluate the rheological characteristics and lubricity of different nanoparticles in water-based mud, with the potential to reduce costs via a decrease in drag and torque during the construction of highly deviated and ERD wells. Extensive results are presented for percentage in torque variation and coefficient of friction before and after aging. Rheology is evaluated via apparent viscosity, plastic viscosity and gel strength variation before and after aging for water-based muds (WBM). Results are included for silica and titanium nanoparticles at different concentrations. These properties were measured before and after aging the mud samples at 80°C during 16 hours at static conditions. The best performance was shown with titanium nanoparticles at a concentration of 0.60 % (w/w) before aging

Cordierite honeycomb supported Mo(VI)/ZrO2 for microwave assisted Pinacol-Pinacolone rearrangement

181-188ZrO2, Mo(VI)/ZrO2, SO42-/ZrO2 and Pt-SO42-/ZrO2 supported on honeycomb monoliths have been prepared and characterized for their physico-chemical properties such as surface acidity, crystalinity, functionality and morphology. These materials have been used as solid acid catalysts in the pinacol rearrangement of benzopinacol under microwave irradiation. A few diols have also been subjected to pinacol rearrangement to obtain a good conversion of rearrangement products with high selectivity. Optimization of reaction conditions has also studied to determine the most suitable reaction conditions for the effective synthesis of pinacolone derivatives. Up to 98% conversion of benzopinacol is observed under a set of optimized reaction conditions. A reactivation and reusability study of zirconia based solid acid catalysts has also performed