Numerical Study on Double Diffusive Convective Flow of Williamson Fluid Over a Vertical Wall

When a fluid with a vertical solute gradient of (−dS/dy)0 is heated laterally, roll cells start to form at the boundary, developing into a series of convective layers. Numerical experiments were performed to investigate the onset of the abovementioned double-diffusive convection under the application of a uniform lateral heat flux. The paper reports the results and discussion of the following aspects of the stability of double-diffusive convection; (i) the relationship between the critical value, (Ra/Rs)c, above which convection cells form along the vertical wall and the nondimensional slot width, (d/L), (ii) the effect of the Lewis number on (Ra/Rs)c. It was also confirmed that values of (Ra/Rs)c as well as H/L (the nondimensional vertical size of incipient cells) obtained in this numerical experiment for wide slot widths (d/L>∼30), agreed well with those obtained previously by physical experiments.

Download Full-text

Free Convective Flow in a Two Enclosure Arrangement With a High Aspect Ratio Side Enclosure Joined to a Large Square Enclosure

10.1115/imece2000-1411 ◽

2000 ◽

Author(s):

Patrick H. Oosthuizen

Keyword(s):

Nusselt Number ◽

Rayleigh Number ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Convective Flow ◽

Numerical Study ◽

Vertical Wall ◽

Heated Wall ◽

Free Convective Flow ◽

Square Enclosure

Abstract A numerical study of free convective flow in a vertical joined two-enclosure arrangement has been undertaken. In this arrangement, a vertical heated wall kept at a uniform high temperature is contained in a high aspect ratio rectangular side enclosure. This enclosure is separated from a larger square enclosure by a vertical dividing wall which is impermeable but offers no resistance to heat transfer. The vertical wall of the main flow enclosure opposite to the dividing wall is maintained at a uniform lower temperature. All remaining walls in both enclosures are adiabatic. The situation considered is an approximate model of a window exposed to a hot outside environment and covered by a plane blind which in turn is exposed to cooled room. The flow has been assumed to be laminar and two-dimensional and results have been obtained for a Prandtl number of 0.7. The effects of Rayleigh number and the dimensionless width of the side enclosure on the Nusselt number have been investigated. The results show that there is a minimum in the Nusselt number variation with side enclosure width for a fixed Rayleigh number. The effect of Rayleigh number on the conditions under which this minimum occurs and on the value of the minimum Nusselt number has been investigated.

Download Full-text

Study of Macrosegregation Defects Formation Caused by Double Diffusive Convective Flow during Solidification of a Binary Alloy

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.283-286.340 ◽

2009 ◽

Vol 283-286 ◽

pp. 340-345 ◽

Cited By ~ 2

Author(s):

Farid Mechighel ◽

Mahfoud Kadja ◽

Mohammed El Ganaoui ◽

Bernard Pateyron

Keyword(s):

Mathematical Model ◽

Finite Volume ◽

Binary Alloy ◽

Convective Flow ◽

Continuum Model ◽

Numerical Study ◽

Finite Volume Approach ◽

The Mathematical Model ◽

Double Diffusive

Numerical study of both the solidification of the binary alloy Al-4.1%wtCu and macrosegregation defects formation have been carried out. The mixture continuum model was used in the development of the mathematical model representing the solidification phenomena. This model included the conservative equations (mass, momentum, energy and species); these equations were numerically solved by using a finite volume approach.

Download Full-text

Numerical Study of Double Diffusive Convection within the Annular Region of Two Concentric Vertical Cylinders

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.374.1 ◽

2017 ◽

Vol 374 ◽

pp. 1-17 ◽

Cited By ~ 1

Author(s):

Mohamed Amine Medebber ◽

Nourddine Retiel

Keyword(s):

Numerical Study ◽

Vertical Wall ◽

Annular Region ◽

Geometrical Parameters ◽

Double Diffusive Convection ◽

Uniform Temperature ◽

Simpler Algorithm ◽

Diffusive Convection ◽

Vertical Cylinders ◽

Double Diffusive

This article reports a numerical study of double-diffusive convection within the annular region of two concentric vertical cylinders. The outer vertical wall is maintained at lower uniform temperature and concentration, while the inner vertical wall is maintained at higher uniform temperature and concentration. The top and bottom horizontal walls are adiabatic and impermeable to mass transfer. The resulting governing equations are solved using a finite volume method. The coupling between the continuity and momentum equations is solved using the SIMPLER algorithm. The compilations have been obtained for Prandtl numbers (Pr) equal to 7.0, and Lewis number (Le) equal to 100. The thermal Rayleigh number (RaT) and height ratio (X) are, respectively, varied in the range 103≤RaT≤106 and 0.0≤X≤1.0. The influence of physical and geometrical parameters on the streamlines, isotherms, isoconcentrations, average Nusselt and Sherwood numbers has been numerically investigated in detail.

Download Full-text