Mahesha Narayana
University of KwaZulu-Natal
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Featured researches published by Mahesha Narayana.
Boundary Value Problems | 2012
Mahesha Narayana; Precious Sibanda; S. S. Motsa; P. G. Siddheshwar
An analysis of double diffusive convection induced by a uniformly heated and salted horizontal wavy surface in a porous medium is presented. The wavy surface is first transformed into a smooth surface via a suitable coordinate transformation and the transformed nonsimilar coupled nonlinear parabolic equations are solved using the Keller box method. The local and average Nusselt and Sherwood numbers are given as functions of the streamwise coordinate and the effects of various physical parameters are discussed in detail. The effects of the Lewis number, buoyancy ratio, and wavy geometry on the dynamics of the flow are studied. It was found, among other observations, that the combined effect of Dufour and Soret parameters is to reduce both heat and mass transfer.MSC:34B15, 65N30, 76M20.
Boundary Value Problems | 2012
Peri K. Kameswaran; Mahesha Narayana; Precious Sibanda; Gilbert Makanda
The paper investigates the radiation effect on the magnetohydrodynamic Newtonian fluid flow over an exponentially stretching sheet. The effects of frictional heating and viscous dissipation on the heat transport are taken into account. The governing partial differential equations are transformed into ordinary differential equations using a suitable similarity transformation. Zero-order analytical solutions of the momentum equation and confluent hypergeometric solutions of heat and mass transport equations are obtained. The accuracy of analytical solutions is verified by numerical solutions obtained using a shooting technique that uses a Runge-Kutta-Felhberg integration scheme and a Newton-Raphson correction scheme. The effects of the radiation parameter, the magnetic parameter, Gebhart and Schmidt numbers on the momentum, heat and mass transports are discussed. The skin friction and heat and mass transfer coefficients for various physical parameters are discussed.
Transport in Porous Media | 2013
Mahesha Narayana; Ahmed A. Khidir; Precious Sibanda; P. V. S. N. Murthy
The paper presents an investigation of the influence of thermal radiation and viscous dissipation on the mixed convective flow due to a vertical plate immersed in a non-Darcy porous medium saturated with a Newtonian fluid. The physical properties of the fluid are assumed to be constant. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing partial differential equations are transformed into a system of ordinary differential equations and solved numerically using a shooting method. The results are analyzed for the effects of various physical parameters such as viscous dissipation, thermal radiation, mixed convection parameters, and the modified Reynolds number on dynamics. The heat transfer coefficient is also tabulated for different values of the physical parameters.
Journal of Applied Mathematics | 2012
Mahesha Narayana; Precious Sibanda
The paper details the use of a nonperturbation successive linearization method to solve the coupled nonlinear boundary value problem due to double-diffusive convection from an inverted cone. Diffusion-thermo and thermal-diffusion effects have been taken into account. The governing partial differential equations are transformed into ordinary differential equations using a suitable similarity transformation. The SLM is based on successively linearizing the governing nonlinear boundary layer equations and solving the resulting higher-order deformation equations using spectral methods. The results are compared with the limited cases from previous studies and results obtained using the Matlab inbuilt bvp4c numerical algorithm and a shooting technique that uses Runge-Kutta-Fehlberg (RKF45) and Newton-Raphson schemes. These comparisons reveal the robustness and validate the usage of the linearisation method technique. The results show that the nonperturbation technique in combination with the Chebyshev spectral collocation method is an efficient numerical algorithm with assured convergence that serves as an alternative to numerical methods for solving nonlinear boundary value problems.
POROUS MEDIA AND ITS APPLICATIONS IN SCIENCE, ENGINEERING, AND INDUSTRY: Fourth International Conference | 2012
Mahesha Narayana; Precious Sibanda
An analysis of the double diffusive convection induced by a horizontal uniformly heated and salted wavy surface in a porous medium is presented. The amplitude of the wavy surface is assumed to be of the order Ra−1/3, where Ra is the Rayleigh number, in order to facilitate the boundary layer approximations. The boundary layer flow is governed by a set of nonlinear parabolic partial differential equations. The wavy surface is transformed into a smooth surface via a suitable coordinate transformation. The transformed non-similar boundary layer governing equations are then solved by the Keller box method. The effects of the Lewis number, buoyancy ratio, and wavy geometry on the dynamics of the flow are studied. The local Nusselt and Sherwood numbers and the average Nusselt and Sherwood numbers are given as functions of streamwise coordinate and the effects of various physical parameters are discussed.
Archive | 2011
Faiz G. Awad; Precious Sibanda; Mahesha Narayana
The study of double-diffusive convection has received considerable attention during the last several decades since this occurs in a wide range of natural settings. The origins of these studies can be traced to oceanography when hot salty water lies over cold fresh water of a higher density resulting in double-diffusive instabilities known as “salt-fingers,” Stern (35; 36). Typical technological motivations for the study of double-diffusive convection range from such diverse fields as the migration of moisture through air contained in fibrous insulations, grain storage systems, the dispersion of contaminants through water-saturated soil, crystal growth and the underground disposal of nuclear wastes. Double-diffusive convection has also been cited as being of particular relevance in the modeling of solar ponds (Akbarzadeh and Manins (1)) and magma chambers (Fernando and Brandt (12)). Double-diffusive convection problems have been investigated by, among others, Nield (28) Baines and Gill (3), Guo et al. (14), Khanafer and Vafai (17), Sunil et al. (37) and Gaikwad et al. (13). Studies have been carried out on horizontal, inclined and vertical surfaces in a porous medium by, among others, Cheng (9; 10), Nield and Bejan (29) and Ingham and Pop (32). Na and Chiou (24) presented the problem of laminar natural convection in Newtonian fluids over the frustum of a cone while Lai (18) investigated the heat and mass transfer by natural convection from a horizontal line source in saturated porous medium. Natural convection over a vertical wavy cone has been investigated by Pop and Na (33). Nakyam and Hussain (25) studied the combined heat and mass transfer by natural convection in a porous medium by integral methods. Chamkha and Khaled (4) studied the hydromagnetic heat and mass transfer by mixed convection from a vertical plate embedded in a uniform porous medium. Chamkha (5) investigated the coupled heat and mass transfer by natural convection of Newtonian fluids about a truncated cone in the presence of magnetic field and radiation effects and Yih (38) examined the effect of radiation in convective flow over a cone. Cheng (6) used an integral approach to study the heat and mass transfer by natural convection from truncated cones in porous media with variable wall temperature and concentration. Khanafer and Vafai (17) studied the double-diffusive convection in a lid-driven enclosure filled with a fluid-saturated porous medium. Mortimer and Eyring (22) used an elementary transition state approach to obtain a simple model for Soret and Dufour effects in thermodynamically ideal mixtures of substances with molecules of nearly equal size. In their model the flow of heat in the Dufour effect was identified as the transport of the enthalpy change of activation as molecules diffuse. 5
International Journal of Heat and Mass Transfer | 2012
Peri K. Kameswaran; Mahesha Narayana; Precious Sibanda; P. V. S. N. Murthy
International Journal of Heat and Mass Transfer | 2012
Mahesha Narayana; Precious Sibanda
Applied Mathematical Modelling | 2013
Mahesha Narayana; Precious Sibanda; P. G. Siddheshwar; G. Jayalatha
International Journal of Heat and Mass Transfer | 2013
Mahesha Narayana; S. N. Gaikwad; Precious Sibanda; R.B. Malge