The Experts below are selected from a list of 120639 Experts worldwide ranked by ideXlab platform

L R Evangelista - One of the best experts on this subject based on the ideXlab platform.

  • a connection between anomalous poisson nernst planck model and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of an anomalous Poisson–Nernst–Planck (PNPA) diffusional model and of equivalent circuits containing constant phase elements (CPEs) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPEs in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained using integro–Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with experimental data obtained from an electrolytic solution.

  • a connection between anomalous poisson nernst planck models and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of anomalous Poisson-Nernst-Planck (PNPA) diffusional models and of equivalent circuits containing constant phase elements (CPE) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPE in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained by using integro-Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with an experimental data obtained from an electrolytic solution.

E K Lenzi - One of the best experts on this subject based on the ideXlab platform.

  • a connection between anomalous poisson nernst planck model and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of an anomalous Poisson–Nernst–Planck (PNPA) diffusional model and of equivalent circuits containing constant phase elements (CPEs) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPEs in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained using integro–Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with experimental data obtained from an electrolytic solution.

  • a connection between anomalous poisson nernst planck models and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of anomalous Poisson-Nernst-Planck (PNPA) diffusional models and of equivalent circuits containing constant phase elements (CPE) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPE in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained by using integro-Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with an experimental data obtained from an electrolytic solution.

Fernanda R G B Silva - One of the best experts on this subject based on the ideXlab platform.

  • a connection between anomalous poisson nernst planck model and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of an anomalous Poisson–Nernst–Planck (PNPA) diffusional model and of equivalent circuits containing constant phase elements (CPEs) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPEs in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained using integro–Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with experimental data obtained from an electrolytic solution.

  • a connection between anomalous poisson nernst planck models and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of anomalous Poisson-Nernst-Planck (PNPA) diffusional models and of equivalent circuits containing constant phase elements (CPE) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPE in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained by using integro-Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with an experimental data obtained from an electrolytic solution.

J L De Paula - One of the best experts on this subject based on the ideXlab platform.

  • a connection between anomalous poisson nernst planck model and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of an anomalous Poisson–Nernst–Planck (PNPA) diffusional model and of equivalent circuits containing constant phase elements (CPEs) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPEs in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained using integro–Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with experimental data obtained from an electrolytic solution.

  • a connection between anomalous poisson nernst planck models and equivalent circuits with constant phase elements
    2013
    Co-Authors: E K Lenzi, J L De Paula, Fernanda R G B Silva, L R Evangelista
    Abstract:

    A connection between the impedance spectroscopy response of anomalous Poisson-Nernst-Planck (PNPA) diffusional models and of equivalent circuits containing constant phase elements (CPE) is established for a typical electrolytic cell. The analysis is carried out in the limit of low frequency in order to highlight the surface effects and to explore how they can be connected to the presence of CPE in the circuit. It is shown that, depending on the choice of the equivalent circuit, the action of these elements can be the same as the one obtained by using integro-Differential Boundary conditions to describe anomalous diffusive processes in the framework of PNPA models. The predictions are also compared with an experimental data obtained from an electrolytic solution.

Oa Beg - One of the best experts on this subject based on the ideXlab platform.

  • Simulation of unsteady natural convection flow of a Casson viscoplastic fluid in a square enclosure utilizing a MAC algorithm
    2020
    Co-Authors: Oa Beg, Venkatadri K, Ts Devi, Cv Lakshmi, Vr Prasad
    Abstract:

    Non-Newtonian fluids are increasingly being deployed in energy systems and materials processing. Motivated by these developments, in the current study, a numerical simulation is performed on two-dimensional, unsteady buoyancy-driven flow in a square cavity filled with non-Newtonian fluid (Casson liquid). The enclosure geometry features vertical isothermal walls (with one at higher temperature than the other) and thermally insulated horizontal walls. The conservation equations for mass, momentum and energy are normalized via appropriate transformations and the resulting dimensionless partial Differential Boundary value problem is solved computationally with a Marker and Cell (MAC) algorithm which features a finite difference scheme along with a staggered grid system. The projection method is employed to evaluate the pressure term. Extensive visualizations of the impact of emerging physical parameters (Rayleigh number and Casson viscoplastic parameter) on streamline and isotherm distributions in the cavity are presented for fixed Prandtl number. Nusselt number i.e. heat transfer rate is increased with rising values of the Casson viscoplastic fluid parameter for any value of Rayleigh number. The density of streamlines increases with increasing values of Casson viscoplastic fluid parameter up to 1. Overall the Casson fluid parameter plays a vital role in controlling the convective heat transfer within the enclosure. The computations are relevant to hybrid solar collectors, materials fabrication (polymer melts) etc

  • Numerical study of slip and radiative effects on magnetic Fe3O4-water-based nanofluid flow from a nonlinear stretching sheet in porous media with Soret and Dufour diffusion
    2020
    Co-Authors: Mm Bhatti, Oa Beg, Cm Khalique, Ta Beg, Kadir A
    Abstract:

    Increasingly sophisticated techniques are being developed for the manufacture of functional nanomaterials. A growing interest is also developing in magnetic nanofluid coatings which contain magnetite nanoparticles suspended in a base fluid and are responsive to external magnetic fields. These nanomaterials are “smart” and their synthesis features high-temperature environments in which radiative heat transfer is present. Diffusion processes in the extruded nanomaterial sheet also feature Soret and Dufour (cross) diffusion effects. Filtration media are also utilized to control the heat, mass and momentum characteristics of extruded nanomaterials and porous media impedance effects arise. Magnetite nanofluids have also been shown to exhibit hydrodynamic wall slip which can arise due to non-adherence of the nanofluid to the Boundary. Motivated by the multi-physical nature of magnetic nanomaterial manufacturing transport phenomena, in this paper, we develop a mathematical model to analyze the collective influence of hydrodynamic slip, radiative heat flux and cross-diffusion effects on transport phenomena in ferric oxide (Fe3O4-water) magnetic nanofluid flow from a nonlinear stretching porous sheet in porous media. Hydrodynamic slip is included. Porous media drag is simulated with the Darcy model. Viscous magnetohydrodynamic theory is used to simulate Lorentzian magnetic drag effects. The Rosseland diffusion flux model is employed for thermal radiative effects. A set of appropriate similarity transformation variables are deployed to convert the original partial Differential Boundary value problem into an ordinary Differential Boundary value problem. The numerical solution of the coupled, multi-degree, nonlinear problem is achieved with an efficient shooting technique in MATLAB symbolic software. The physical influences of Hartmann (magnetic) number, Prandtl number, Richardson number, Soret (thermo-diffusive) number, permeability parameter, concentration buoyancy ratio, radiation parameter, Dufour (diffuso-thermal) parameter, momentum slip parameter and Schmidt number on transport characteristics (e.g. velocity, nanoparticle concentration and temperature profiles) are investigated, visualized and presented graphically. Flow deceleration is induced with increasing Hartmann number and wall slip, whereas flow acceleration is generated with greater Richardson number and buoyancy ratio parameter. Temperatures are elevated with increasing Dufour number and radiative parameter. Concentration magnitudes are enhanced with Soret number, whereas they are depleted with greater Schmidt number. Validation of the MATLAB computations with special cases of the general model is included. Further validation with generalized Differential quadrature (GDQ) is also included

  • Melting heat transfer analysis of electrically conducting nanofluid flow over an exponentially shrinking/stretching porous sheet with radiative heat flux under magnetic field
    2020
    Co-Authors: Venkatadri K, Oa Beg, Sa Gaffar, Rajarajeswari P, Vr Prasad, Khan Bmh
    Abstract:

    Modern magnetic nanomaterials processing operations are progressing rapidly and require increasingly sophisticated mathematical models for their optimization. Stimulated by such developments, in this article, a theoretical and computational study of steady magnetohydrodynamic (MHD) flow of nanofluid from an exponentially stretching/shrinking permeable sheet with melting (phase change) and radiative heat transfer is presented. Wall transpiration i.e. suction and blowing (injection) is included. Buongiorno’s nanofluid model is deployed which simulates the effects of Brownian motion and thermophoresis. The transport equations and Boundary conditions are normalized via similarity transformations and appropriate variables and similarity solutions are shown to depend on the transpiration parameter. The emerging dimensionless nonlinear coupled ordinary Differential Boundary value problem is solved numerically with the Newton-Fehlberg iteration technique. Validation with special cases from the literature is included. Increasing magnetic field i.e. Hartmann number is observed to elevate nanoparticle concentration and temperature whereas it damps the velocity. Higher values of melting parameter consistently decelerate the Boundary layer flow and suppress temperature and nanoparticle concentration. Higher radiative parameter strongly increases temperature (and thermal Boundary layer thickness) and weakly accelerates the flow. Increasing Brownian motion reduces nanoparticle concentrations whereas greater thermophoretic body force strongly enhances them. Nusselt number and Sherwood number are decreased with increasing Hartmann number whereas they are elevated with stronger wall suction and melting parameter

  • Biomathematical model for gyrotactic free-forced bioconvection with oxygen diffusion in near-wall transport within a porous medium fuel cell
    2020
    Co-Authors: Ni Nima, Oa Beg, Ferdows M, Kuharat S, Alzahrani F
    Abstract:

    Bioconvection has shown significant promise for environmentally friendly, sustainable “green” fuel cell technologies. The improved design of such systems requires continuous refinements in biomathematical modelling in conjunction with laboratory and field testing. Motivated by exploring deeper the near-wall transport phenomena involved in bioinspired fuel cells, in the present article, we examine analytically and numerically the combined free-forced convective steady Boundary layer flow from a solid vertical flat plate embedded in a Darcian porous medium containing gyrotactic microorganisms. Gyrotaxis is one of many taxes exhibited in biological microscale transport, and other examples include magneto-taxis, photo-taxis, chemotaxis and geo-taxis (reflecting the response of micro-organisms to magnetic field, light, chemical concentration or gravity, respectively). The bioconvection fuel cell also contains diffusing oxygen species which mimics the cathodic behavior in a proton membrane exchange (PEM) system. The vertical wall is maintained at iso-solutal (constant oxygen volume fraction and motile micro-organism density) and iso-thermal conditions. Wall values of these quantities are sustained at higher values than the ambient temperature and concentration of oxygen and biological micro-organism species. Similarity transformations are applied to render the governing partial Differential equations for mass, momentum, energy, oxygen species and micro-organism species density into a system of ordinary Differential equations. The emerging eight order nonlinear coupled, ordinary Differential Boundary value problem features several important dimensionless control parameters, namely Lewis number (Le), buoyancy ratio parameter i.e. ratio of oxygen species buoyancy force to thermal buoyancy force (Nr), bioconvection Rayleigh number (Rb), bioconvection Lewis number (Lb), bioconvection Péclet number (Pe) and the mixed convection parameter spanning the entire range of free and forced convection. The transformed non-linear system of equations with Boundary conditions is solved numerically by a finite difference method with central differencing, tridiagonal matrix manipulation and an iterative procedure. Computations are validated with the symbolic Maple 14.0 software. The influence of buoyancy and bioconvection parameters on the dimensionless temperature, velocity, oxygen concentration and motile microorganism density distribution, Nusselt, Sherwood and gradient of motile microorganism density are studied. The work clearly shows the benefit of utilizing biological organisms in fuel cell design and presents a logical biomathematical modelling framework for simulating such systems. In particular, the deployment of gyrotactic micro-organisms is shown to stimulate improved transport characteristics in heat and momentum at the fuel cell wall

  • Computational study of unsteady couple stress magnetic nanofluid flow from a stretching sheet with ohmic dissipation
    2019
    Co-Authors: Kumar M, Gj Reddy, Nn Kumar, Oa Beg
    Abstract:

    To provide a deeper insight of the transport phenomena inherent to the manufacturing of magnetic nano-polymer materials, in the present work a mathematical model is developed for time-dependent hydromagnetic rheological nanopolymer Boundary layer flow and heat transfer over a stretching sheet in the presence of a transverse static magnetic field. Joule heating (Ohmic dissipation) and viscous heating effects are included since these phenomena arise frequently in magnetic materials processing. Stokes’ couple stress model is deployed to simulate non-Newtonian micro-structural characteristics. The Tiwari-Das nanoscale model is adopted which permits different nano-particles to be simulated (in this article both copper-water and aluminium oxide-water nanofluids are considered). Similarity transformations are utilized to convert the governing partial Differential conservation equations into a system of coupled, nonlinear ordinary Differential equations with appropriate wall and free stream Boundary conditions. The shooting technique is used to solve the reduced nonlinear coupled ordinary Differential Boundary value problem via MATLAB symbolic software. Validation with published results from the literature is included for the special cases of non-dissipative and Newtonian nanofluid flows. Fluid velocity and temperature profiles for both Copper and Aluminium Oxide (Al2O3) nanofluids are observed to be enhanced with greater non-Newtonian couple stress parameter and magnetic parameter whereas the opposite trend is computed with greater values of unsteadiness parameter. The Boundary layer flow is accelerated with increasing buoyancy parameter, elastic sheet stretching parameter and convection parameter. Temperatures are generally increased with greater couple stress rheological parameter and are consistently higher for the Aluminium oxide nanoparticle case. Temperatures are also boosted with magnetic parameter and exhibit an overshoot near the wall when magnetic parameter exceeds unity (magnetic force exceeds viscous force). A decrease in temperatures is induced with increasing sheet stretching parameter. Increasing Eckert number elevates temperatures considerably. With greater nanoparticle volume fraction both skin friction and Nusselt number are elevated and copper nano-particles achieve higher magnitudes than aluminium oxide