Weakly Nonlinear Double-Diffusive Oscillatory Magneto-Convection Under Gravity Modulation

2020 ◽  
Vol 18 (9) ◽  
pp. 725-738
Author(s):  
Palle Kiran ◽  
S. H. Manjula
Keyword(s):  
Mass Transfer ◽  
Prandtl Number ◽  
Gravity Field ◽  
Heat And Mass Transfer ◽  
Landau Equation ◽  
Perturbation Technique ◽  
Critical Rayleigh Number ◽  
Oscillatory Mode ◽  
Stationary Mode ◽  
Double Diffusive

An imposed time-periodic gravity field effect on double-diffusive magneto-convection for oscillatory mode has been investigated. The gravity field consisting of steady and periodic modes. A layer is confined with an electrically conducting fluid with Boussines q approximation and heated from below cooled from above. While using the perturbation technique we study nonlinear double-diffusive convection just above the critical state of the onset convection. The growth rate of the disturbances is confined with a critical Rayleigh number to investigate oscillatory convection. Analysis of finite- amplitude convection has been derived through the complex Ginzburg-Landau equation (CGLE). The convective heat and mass transfer obtained through CGLE at third-order under solvability conditions. This convective amplitude is required to estimate heat and mass transfer in terms of the Nusselt and Sherwood numbers. It is found that increasing the frequency of modulation causes diminishing heat and mass transfer. The effect of Prandtl number Pr, magnetic Prandtl number Pm, and amplitude δ enhances heat/mass transfer. It is found that an oscillatory mode of convection enhances the heat and mass transfer than the stationary mode. Further, streamlines, isotherms, and isohalines have their usual nature on double-diffusive magnetoconvection.

scholarly journals Convective heat and mass transfer in a non-Newtonian-flow formation in Couette motion in magnetohydrodynamics with time-varing suction

2011 ◽  
Vol 15 (3) ◽  
pp. 749-758 ◽  
Author(s):  
Faiza Salama
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Perturbation Technique ◽  
Transverse Magnetic ◽  
Integration Scheme ◽  
Stream Velocity ◽  
Grashof Number ◽  
Moving Wall ◽  
Pressure Parameter

An analysis is carried out to study the effect of heat and mass transfer on a non-Newtonian-fluid between two infinite parallel walls, one of them moving with a uniform velocity under the action of a transverse magnetic field. The moving wall moves with constant velocity in the direction of fluid flow while the free stream velocity is assumed to follow the exponentially increasing small perturbation law. Time-dependent wall suction is assumed to occur at permeable surface. The governing equations for the flow are transformed into a system of nonlinear ordinary differential equations by perturbation technique and are solved numerically by using the shooting technique with fourth order Runge-Kutta integration scheme. The effect of non-Newtonian parameter, magnetic pressure parameter, Schmidt number, Grashof number and modified Grashof number on velocity, temperature, concentration and the induced magnetic field are discussed. Numerical results are given and illustrated graphically for the considered Problem.

Numerical simulation of unsteady double-diffusive natural convection within an inclined parallelepipedic enclosure

2014 ◽  
Vol 25 (11) ◽  
pp. 1450058 ◽  
Author(s):  
Fakher Oueslati ◽  
Brahim Ben-Beya ◽  
Taieb Lili
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Three Dimensional ◽  
Transfer Rates ◽  
Flow Energy ◽  
Wide Range ◽  
Inclination Angles ◽  
Volume Method ◽  
Buoyancy Ratio ◽  
Double Diffusive

Unsteady three-dimensional (3D) double diffusive convection in tilted enclosure having a parallelepipedic shape has been analyzed numerically. The governing unsteady, 3D flow, energy and concentration transport equations, have been solved using an accelerated multigrid implicit volume method. Main attention was paid to the effects of the Rayleigh number Ra , buoyancy ratio N and the inclination angle γ of the cavity on the flow structure and heat and mass transfer rates. Typical distributions of velocity contours, temperature and concentration fields in wide range of defining parameters 103 ≤ Ra ≤ 2 × 104, -5 ≤ N ≤ 5 have been obtained. It is found, that the optimal heat and mass transfer rates for the aiding situation have been observed at two particular inclination angles namely 30° and 75° about the horizontal direction. It should be noted that the flow undergoes a periodic behavior for particular parameters Ra = 104 and γ = 75° according to the aiding flow case. The results also suggest that when N is in range -2 ≤ N ≤ -0.6, the flow continues to be three-dimensional keeping different heat and mass rates. Furthermore, it has been argued that the 2D assumption can be adopted for the 3D flows when the buoyancy ratio N is in range (-0.5–0).

Heat and Mass Transfer of a MHD Flows of An Oldroyd 8-Constant Nano-Fluid Through a Non-Darcy Porous Medium

2017 ◽  
Vol 14 (1) ◽  
pp. 321-329
Author(s):  
Abeer A Shaaban
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Porous Medium ◽  
Differential Equations ◽  
Prandtl Number ◽  
Heat And Mass Transfer ◽  
Induced Magnetic Field ◽  
Linear Ordinary Differential Equations ◽  
Nano Fluid ◽  
Non Linear

Explicit finite-difference method was used to obtain the solution of the system of the non-linear ordinary differential equations which transform from the non-linear partial differential equations. These equations describe the steady magneto-hydrodynamic flow of an oldroyd 8-constant non-Newtonian nano-fluid through a non-Darcy porous medium with heat and mass transfer. The induced magnetic field was taken into our consideration. The numerical formula of the velocity, the induced magnetic field, the temperature, the concentration, and the nanoparticle concentration distributions of the problem were illustrated graphically. The effect of the material parameters (α1 α2), Darcy number Da, Forchheimer number Fs, Magnetic Pressure number RH, Magnetic Prandtl number Pm, Prandtl number Pr, Radiation parameter Rn, Dufour number Nd, Brownian motion parameter Nb, Thermophoresis parameter Nt, Heat generation Q, Lewis number Le, and Sort number Ld on those formula were discussed specially in the case of pure Coutte flow (U0 = 1, d <inline-formula> <mml:math display="block"> <mml:mrow> <mml:mover accent="true"> <mml:mi>P</mml:mi> <mml:mo stretchy="true">^</mml:mo> </mml:mover> </mml:mrow> </mml:math> </inline-formula> /dx = 0). Also, an estimation of the global error for the numerical values of the solutions is calculated by using Zadunaisky technique.

Sign in / Sign up

Export Citation Format

Share Document