The structure of (linearly) stable double diffusive flow patterns in a laterally heated stratified liquid

1995 ◽  
Vol 7 (3) ◽  
pp. 680-682 ◽  
Author(s):  
E. Jurjen Kranenborg ◽  
Henk A. Dijkstra
1999 ◽  
Vol 400 ◽  
pp. 333-353 ◽  
Author(s):  
I. SEZAI ◽  
A. A. MOHAMAD

A three-dimensional mathematical model based on the Brinkman extended Darcy equation has been used to study double-diffusive natural convection in a fluid-saturated porous cubic enclosure subject to opposing and horizontal gradients of temperature and concentration. The flow is driven by conditions of constant temperature and concentration imposed along the two vertical sidewalls of the cubic enclosure, while the remaining walls are impermeable and adiabatic. The numerical simulations presented here span a wide range of porous thermal Rayleigh number, buoyancy ratio and Lewis number to identify the different steady-state flow patterns and bifurcations. The effect of the governing parameters on the domain of existence of the three-dimensional flow patterns is studied for opposing flows (N < 0). Comprehensive Nusselt and Sherwood number data are presented as functions of the governing parameters. The present results indicate that the double-diffusive flow in enclosures with opposing buoyancy forces is strictly three-dimensional for a certain range of parameters. At high Lewis numbers multiple dipole vortices form in the transverse planes near the horizontal top and bottom surfaces, which the two-dimensional models fail to detect. The dipolar vortex structures obtained are similar to those created in laboratory experiments by the injection of fluid into a stratified medium.


2002 ◽  
Vol 464 ◽  
pp. 311-344 ◽  
Author(s):  
I. SEZAI

In the present study the existence of multiple three-dimensional double-diffusive flow patterns in a horizontal rectangular porous cavity of a square cross-section, having horizontal aspect ratios Ax = Ay = 2 is investigated numerically. Opposing vertical gradients of temperature and concentration are applied between the two horizontal walls of the cavity, where the solute gradient is destabilizing against a stabilizing temperature gradient. All vertical walls are considered to be impermeable and adiabatic. The Brinkman and Forchheimer terms are included in the momentum equations where the convective terms are retained. The effect of the buoyancy ratio, N, thermal Rayleigh number, RaT and Lewis number, Le, on the formation of multiple flow patterns is investigated over a wide range of parameters. Altogether 36 symmetric flow structures have been identified when each of the parameters N, RaT, and Le is varied independently, keeping the others as constants. The results of the calculations are presented in terms of the average Sherwood number curves consisting of different solution branches, where transitions between the branches are indicated. The flow patterns are classified according to their symmetry properties and the type of symmetries broken or preserved are identified during the bifurcation processes.


2017 ◽  
Vol 27 (12) ◽  
pp. 2858-2878 ◽  
Author(s):  
B.J. Gireesha ◽  
M. Archana ◽  
Prasannakumara B.C. ◽  
R.S. Reddy Gorla ◽  
Oluwole Daniel Makinde

Purpose This paper aims to deal with the study of heat and mass transfer on double-diffusive three-dimensional hydromagnetic boundary layer flow of an electrically conducting Casson nanofluid over a stretching surface. The combined effects of nonlinear thermal radiation, magnetic field, buoyancy forces, thermophoresis and Brownian motion are taken into consideration with convective boundary conditions. Design/methodology/approach Similarity transformations are used to reduce the governing partial differential equations into a set of nonlinear ordinary differential equations. The reduced equations were numerically solved using Runge–Kutta–Fehlberg fourth-fifth-order method along with shooting technique. Findings The impact of several existing physical parameters such as Casson parameter, mixed convection parameter, regular buoyancy ratio parameter, radiation parameter, Brownian motion parameter, thermophoresis parameter, temperature ratio parameter on velocity, temperature, solutal and nanofluid concentration profiles are analyzed through graphs and tables in detail. It is found that the solutal component increases for Dufour Lewis number, whereas it decreases for nanofluid Lewis number. Moreover, velocity profiles decrease for Casson parameter, while the Nusselt number increases for Biot number, radiation and temperature ratio parameter. Originality/value This paper is a new work related to three-dimensional double-diffusive flow of Casson nanofluid with buoyancy and nonlinear thermal radiation effect.


2010 ◽  
Vol 297-301 ◽  
pp. 97-104 ◽  
Author(s):  
Farid Mechighel ◽  
Bernard Pateyron ◽  
Mahfoud Kadja ◽  
Mohammed El Ganaoui ◽  
S. Dost

A numerical simulation study has been carried out to examine the effect of a static magnetic field on the solidification process of an alloy. A mathematical model, based on the continuum model, was developed for the computation of a transient double-diffusive fluid flow under Lorentz body force. The model includes conservation of mass and momentum, heat, species and electrical charge balance equations. The simulation domain was selected as a cavity filled with a metallic alloy and differentially heated, which may be taken as a Bridgman model domain used in the crystal growth process. The solution is carried out by using a Finite Volume Method. Study of the direction and the intensity of the applied magnetic field effects on stabilizing the double diffusive flow field were also carried out. Simulation results indicate that the use of a static, magnetic field in this growth setup is effective in suppressing natural convection in the solution.


2016 ◽  
Author(s):  
Irfan Anjum Badruddin ◽  
T. M. Yunus Khan ◽  
Salman Ahmed N. J. ◽  
Sarfaraz Kamangar

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