Abstract

A similarity solution for the steady hydromagnetic convective heat and mass transfer with slip flow from a spinning disk with viscous dissipation and Ohmic heating yields a system of non-linear, coupled, ordinary differential equations. These equations are analytically solved by applying a newly developed method namely the DTM-Pade technique which is a combination of the Differential Transform Method (DTM) and the Pade approximation. A full analytical solution is presented, as a benchmark for alternative numerical solutions. DTM-Pade is implemented without requiring linearization, discretization, or perturbation, and holds significant potential for solving strongly nonlinear differential equations which arise frequently in fluid dynamics. The regime studied is shown to be controlled by the slip parameter (γ), magnetohydrodynamic body force parameter (M), Eckert (viscous heating) number (Ec), Schmidt number (Sc), Soret number (Sr), Dufour number (Du) and Prandtl number (Pr). The influence of selected parameters on the evolution of dimensionless velocity, temperature and concentration distributions is studied graphically. Increasing magnetic field (M) is found to significantly inhibit the radial (f) and tangential (g) velocities, but to accentuate the axial velocity field (h); furthermore temperature (θ) and concentration (φ) are both enhanced with increasing M. Increasing Soret number (Sr) acts to boost the dimensionless concentration (φ). Temperatures are significantly elevated in the boundary layer regime with a rise in Eckert number (Ec). Excellent correlation between the DTM-Pade technique and numerical (shooting) solutions is achieved. The model has important applications in industrial energy systems, process mechanical engineering, electromagnetic materials processing and electro-conductive chemical transport processes.

Highlights

  • Hydromagnetic flow with heat and mass transfer from a rotating disk is a fundamental regime of interest in diverse branches engineering including magnetic materials processing [1], industrial energy conversion [2], magnetohydrodynamic tribological systems [3,4], rotating disk voltammetry in chemical synthesis [5] etc

  • The flow regime is controlled by a number of thermophysical parameters: magnetohydrodynamic body force parameter (M), Soret number (Sr), Dufour number (Du), Eckert number (Ec), Prandtl number (Pr) and Schmidt number (Sc) and slip parameter ( )

  • We adopt a Prandtl number (Pr) corresponding to air at 20 Celsius i.e. Pr = 0.71. At this Prandtl number, the diluting chemical species generally encountered in mechanical engineering operations posses a Schmidt number (Sc) in the range from 0.1 to 10

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Summary

Introduction

Hydromagnetic flow with heat and mass transfer from a rotating disk is a fundamental regime of interest in diverse branches engineering including magnetic materials processing [1], industrial energy conversion [2], magnetohydrodynamic tribological systems [3,4], rotating disk voltammetry in chemical synthesis [5] etc. Sibanda and Makinde [20] used a Newton-Raphson shooting method along with fourth-order Runge-Kutta integration algorithm to study the steady hydromagnetic convection from a spinning disk embedded in a porous medium with viscous and Ohmic dissipation, and Hall currents. They showed that magnetic field inhibits the flow due to the opposing Lorentz force generated by the magnetic field and that both magnetic field and the Eckert number (dissipation parameter) enhance the heat transfer efficiency.

Mathematical Model
The Padé Approximants
Analysis with DTM-Padé Simulation
Results and Discussion
Conclusions
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